Younger Dryas cooling event said to be comet related

From the University of California – Santa Barbara: A cataclysmic event of a certain age

Geologist James Kennett and an international team narrow the date of an anomalous cooling event most likely triggered by a cosmic impact

 This map shows the Younger Dryas Boundary locations that provided data for the analysis. Credit: UCSB

This map shows the Younger Dryas Boundary locations that provided data for the analysis. Credit: UCSB

At the end of the Pleistocene period, approximately 12,800 years ago­ — give or take a few centuries — a cosmic impact triggered an abrupt cooling episode that earth scientists refer to as the Younger Dryas.

New research by UC Santa Barbara geologist James Kennett and an international group of investigators has narrowed the date to a 100-year range, sometime between 12,835 and 12,735 years ago. The team’s findings appear today in the Proceedings of the National Academy of Sciences.

The researchers used Bayesian statistical analyses of 354 dates taken from 30 sites on more than four continents. By using Bayesian analysis, the researchers were able to calculate more robust age models through multiple, progressive statistical iterations that consider all related age data.

“This range overlaps with that of a platinum peak recorded in the Greenland ice sheet and of the onset of the Younger Dryas climate episode in six independent key records,” explained Kennett, professor emeritus in UCSB’s Department of Earth Science. “This suggests a causal connection between the impact event and the Younger Dryas cooling.”

In a previous paper, Kennett and colleagues conclusively identified a thin layer called the Younger Dryas Boundary (YDB) that contains a rich assemblage of high-temperature spherules, melt-glass and nanodiamonds, the production of which can be explained only by cosmic impact. However, in order for the major impact theory to be possible, the YDB layer would have to be the same age globally, which is what this latest paper reports.

“We tested this to determine if the dates for the layer in all of these sites are in the same window and statistically whether they come from the same event,” Kennett said. “Our analysis shows with 95 percent probability that the dates are consistent with a single cosmic impact event.”

All together, the locations cover a huge range of distribution, reaching from northern Syria to California and from Venezuela to Canada. Two California sites are on the Channel Islands off Santa Barbara.

However, Kennett and his team didn’t rely solely on their own data, which mostly used radiocarbon dating to determine date ranges for each site. They also examined six instances of independently derived age data that used other dating methods, in most cases counting annual layers in ice and lake sediments.

Two core studies taken from the Greenland ice sheet revealed an anomalous platinum layer, a marker for the YDB. A study of tree rings in Germany also showed evidence of the YDB, as did freshwater and marine varves, the annual laminations that occur in bodies of water. Even stalagmites in China displayed signs of abrupt climate change around the time of the Younger Dryas cooling event.

“The important takeaway is that these proxy records suggest a causal connection between the YDB cosmic impact event and the Younger Dryas cooling event,” Kennett said. “In other words, the impact event triggered this abrupt cooling.

“The chronology is very important because there’s been a long history of trying to figure out what caused this anomalous and enigmatic cooling,” he added. “We suggest that this paper goes a long way to answering that question and hope that this study will inspire others to use Bayesian statistical analysis in similar kinds of studies because it’s such a powerful tool.”


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July 27, 2015 2:43 pm

This is a fascinating inquiry. I’ve been watching the various proponents and detractors of this theory go back and forth for a few years now – one study will say it was a comet, another will say no, that is completely wrong. The younger Dryas is an odd event, difficult to expain, and this does appear to fit the bill – also would have had a lot to do with the extinction of the North American megafauna. (maybe some link to the frozen mammoths in Siberia? There’s always been some odd questions about why so many got frozen so completely on what appeared to have been a balmy day)
A comet hitting the laurentide ice sheet (ice against ice) would have created a huge blast, but left no crater.

Curious George
Reply to  wws
July 27, 2015 2:52 pm

High-temperature spherules, melt-glass and nanodiamonds …

John F. Hultquist
Reply to  wws
July 27, 2015 2:57 pm

… a rich assemblage of high-temperature spherules, melt-glass and nanodiamonds,
Ice against ice and no crater — something doesn’t fit!

Reply to  John F. Hultquist
July 27, 2015 4:03 pm

How about most of the blast was into ice, but it did hit bottom and produce a limited amount of hot ejecta?

Reply to  John F. Hultquist
July 27, 2015 4:38 pm

comets tend to be rich in carbon [diamonds]. And no comets is pure water [or just water and hydrocarbons]. Or there would be all kinds of impurity, and the platinum could a higher abundance
then from normal rain and dust found in Earth atmosphere.

Reply to  John F. Hultquist
July 27, 2015 4:56 pm

Even comets have a lot of dust in them. And if was an asteroid not a comet …

Reply to  John F. Hultquist
July 27, 2015 9:08 pm

Comets are not pure ice. The main theory for comets is that they are “dirty snowballs”, and there are signs that some comets are more like “snowy dirtballs”. Many comets have significant chunks of something that can form meteors achieving “fireball” brightness (visual magnitude generally -4 like that of Venus in its brighter times or brighter) according to the daily fireball report at on many days, mainly when a meteor shower associated with a known comet is in progress. Extraterrestrial objects of asteroid and comet nucleus size have a higher concentration of platinum and iridium than Earth’s crust does, because Earth’s share of these extremely dense metals got concentrated into Earth’s metallic core.

Steve Garcia
Reply to  John F. Hultquist
July 27, 2015 11:11 pm

Who says ice against ice? You? The comets as “dirty snowballs” idea that doesn’t match reality? 67P, just visited recently was found to have some surface ice and was mostly rock. Comet Itokawa, ditto. Halley’s? Also mostly rock. The closer we come to comets, the more they seem to not be dirty snowballs. Some might be, but certainly some aren’t.

Geologist Down The Pub Sez
Reply to  John F. Hultquist
July 28, 2015 4:00 pm

Does the comet have to be all ice? Many contain silicates and metals, so the model could be made to work.

Steve Garcia
Reply to  John F. Hultquist
July 30, 2015 2:40 am

@Geologist Down The Pub Sez July 28, 2015 at 4:00 pm
“Does the comet have to be all ice? Many contain silicates and metals, so the model could be made to work.”
Correct. The urban myth that comets are dirty ice balls has been shown to be not so very true. Some are. Not even close to all of them. As I understand it – and I might be wrong – before we WENT to comets, we had to rely on two basic lines of evidence. One was spectrographic evidence, looking for elements in the spectrae of the reflected light. That can only look at the surface. The second way was to try to measure the diameter of a comet, then by its diversions due to Jupiter and other bodies (if we could) to calculate a total mass. comparing the two, we could arrive at a “bulk density”. Using that we cold elminate some possibles. If the bulk density was too low we knew it couldn’t be iron-nickel or even silicate (much) – unless it was very porous – which we couldn’t really know from telescopes. Low desnity suggested maybe a lot of ice, but wwe coulnd’t be sure.
So, we visited Halley’s comet in 1986.
[Wiki]: “The missions also provided data that substantially reformed and reconfigured these ideas; for instance, now it is understood that the surface of Halley is largely composed of dusty, non-volatile materials, and that only a small portion of it is icy.”
Comet Tempel 1 was impacted by Deep Impact, and this from
“Dust emanates from the comet in frequent outbursts, likely a result of being warmed by the Sun. The dust kicked up by the impact was not the same as surface dust, but it spread through space and dissipated in a manner similar to the natural outbursts.
While more analysis is needed, the interior is clearly different from the surface. . .
. . .Inside, the comet harbors a relatively high concentration of organic compounds, the stuff from which life is made. The organics were more prevalent during and after the outburst than the water and carbon dioxide that routinely escape from the nucleus, or hard core of the comet.
In recent years, our impression of comets has shifted from dirty snowballs to snowy dirtballs. That latter description holds true with comet Tempel 1, A’Hearn said.
There is more dust than ice, A’Hearn said, but the ratio is less than 10-to-1. More significant to the new data is the revelation that there’s not much there.”
And we visited comet 67P/Churyumov-Gerasimenko in 2014. Same result – a “snowy dirtball” more than a dirty snowball.
“”We’re a bit surprised at just how unreflective the comet’s surface is and how little evidence of exposed water-ice it shows,” Alan Stern, Alice principal investigator at the Southwest Research Institute in Boulder, Colorado, said in a statement.” (
This is informative, but dammit, it is nothing but people saying their assumptions about what is being found, not what was actually found. “Hard as ice” could mean anything – including rock – but not dust. Almost every statement is waffled.

Reply to  wws
July 27, 2015 11:26 pm

Wws: “A comet hitting the laurentide ice sheet (ice against ice) would have created a huge blast, but left no crater.”
Prime candidate could be Nastapoka’s arc, a perfect arc of a circle
If it was comet than it would be a huge lump of iron slowly sinking into the Mohorovičić discontinuity and eventually into the Earth’s mantle.
Strength of the Earth’s magnetic field (highest in the N. Hemisphere) following solar activity (reverse correlation) and the extreme negative gravity anomaly (more images HERE) make this area absolutely unique anywhere on the planet, perhaps best expressed in these few words:
Ordinary in no way is the Grand Old Hudson Bay
the centre of the ancient Laurentide
climbing up the isostatic stairway
in adulation of the sun, from Akhenaten to Svalgaard
the incontestable ruler of the North Atlantic Oscillations
for centuries past, the host to the true magnetic pole
boasting the lowest of the low in the gravity computations
with mystifying Nastapoka’s arc perfections
no other place on this beautiful blue globe
can equal the splendours of nature bestowed onto you
We salute you the Grand Old Hudson Bay.

Reply to  vukcevic
July 28, 2015 1:07 am

correction: should be: not an ice comet but asteroid originated meteorite or similar.

Jay Hope
Reply to  wws
July 30, 2015 5:45 am

Blame it on anything, just don’t say the Sun had anything to do with it!

July 27, 2015 2:45 pm

Merely suggests? I thought that the science was settled; that correlation was causation.

Steve Garcia
Reply to  Jquip
July 27, 2015 11:25 pm

Yes, to correlation, in the YDB studies. This may be the first study that has gotten past the lab testing for materials, which seem to indicate that the energy required and temperatures required for those materials was higher than terrestrial processes, including volcanoes. The involved scientists have not previously gone past the lab tests, because they know that if the lab tests of the materials doesn’t fly, then they can drop it and go on to other research. They didn’t want to put the cart ahead of the horse.
This current paper seems to indicate that they may be satisfied with the lab results and that there is nothing more they can do, so they can begin to go on to the OTHER aspects of such an impact scenario – mammoths, at some point, and perhaps mega-tsunamis, and the fires and the climate effects.
I’d think that in order to take that next step they have to see – as this study attempts – Did it all even happen at the same time? Again, if it shows that the effects that led to the lab results were spread over 500 years, then they would be barking up the wrong tree. NON correlation – falsification – would certainly be a clue, whereas correlation still keeps the possibility open, wouldn’t you say?
Quite literally, MUCH of the evidence in academic papers is evidence that “suggest” a hypothesis can be true, or evidence that “is consistent with” it, or evidence that does not refute the possibility. There are many shades of grey in evidence, and the more remote in time evidence is, the more “iffy” it will be – the more grey. Bayesian analysis seems to be a tool for dealing with the varying levels of certainty. Why WOULDN’T they use it to find out if they should just pack up their bags and go on to something else? But they weren’t going to use it until the bits of evidence were as solid as they could get it.
And whereas all this happened early 13,000 years ago, how would YOU propose they try to tie things to the same time frame? Take a time machine and go back and ask people?

July 27, 2015 2:51 pm

There is one thing for sure, the planet has been hit many times by a comet. Some of those comets must have been huge. If a huge comet hits the planet, then there has got to be some sort of large scale effect. I think this team is on to something.

Reply to  markstoval
July 27, 2015 9:13 pm

Many times by A comet?

Reply to  Jeff Alberts
July 28, 2015 8:02 am

Yes, by comets. Interesting read on Wikipedia about the possible influence of the galactic tide, bringing Oort cloud objects into the inner solar system. There appears to be about a 25% increase in comet impacts in the years after we pass through the galactic disk (when the tide is at a maximum). Very interesting stuff.

Reply to  Jeff Alberts
July 28, 2015 8:12 am

Darn thing kept backing up and hitting us again!

Steve Garcia
Reply to  markstoval
July 30, 2015 6:24 am

Be a little careful, though, about the terms comet and meteor. Every other non-gaseous body out there (except now Pluto!) is covered in craters. So, clearly, many have also come to visit Earth. When? The astronomers say it was almost all a very long time ago.
They may be right. They may not be. Not all of them are so sure that we may be a bit at risk, even now. (But at least they aren’t running around like Chicken Little, screaming “The Sky is FALLING!. The Sky is FALLING!”.)
Earth is VERY much protected by our atmosphere. Small stuff has a very hard time making it through our atmosphere without doing like the meteor in Chelyabinsk in 2013 – melt away and/or turns into a fireball, before ever getting to the surface. THAT is a GOOD THING. Our atmosphere probably got hit by 10 times the asteroids and meteoroids and comets as the Moon. And without our atmosphere, the Earth would probably look WORSE than the Moon – more cratered. Thea atmosphere not only GIVES us life, but it also SAVES our lives. All those thousands of small meteors that hit every day and turn into shooting stars – on the MOon and Mars and Mercury and all those moons in the solar system all of those meteors would hit REALLY hard on the Earth’s surface, if we didn’t have an atmosphere. Anything on the surface would be at terrible risk of getting “shot” by some object going 5 to 35 times as fast as a bullet. Normal bullets are about 2200 km/sec. That is about 60% of 1 km/sec. Meteors come in at at least 10 km/sec, and comets can come in at 70 km/ sec.
That stuff IS out there. Doing due diligence and trying to find all of them is a good idea, but no one is running around panicking about it. We may not get hit by a dnageous one for a few thousand years. Just in case – since we CAN – it hasn’t hurt us to check out just to be sure.
The YDB scientists (about 26 on this current paper) are not even talking about future risk. They are looking back in time to see if something whacked us 9000 years before Stonehenge. The more they’ve looked at it, the more it looks like yes.

Sturgis Hooper
Reply to  Steve Garcia
July 30, 2015 6:43 am

The more disinterested scientists look at it, the higher their certainty that the conjecture is a fantasy.
Large impacts obviously do occur and one could have happened that recently, although it’s highly unlikely. It’s just that there is no evidence for it and all the evidence in the world against it.
Asteroids with a one km diameter strike earth every 500,000 years on average. Larger collisions, of five-km objects, happen approximately once in twenty million years. The last known impact by an object of 10 km or more in diameter was the K-T (or P) extinction event 66 million years ago.

Steve Garcia
Reply to  Steve Garcia
July 30, 2015 12:16 pm

SH –
“Disinterested scientists”?
Oh yeah? Name them. Skeptics count or don’t they? If you name skeptics, then they aren’t disinterested. Name some the skeptics have convinced..
Oh, I am sorry, this is such a bad idea that they don’t NEED convincing by skeptics.
But name a few.

Steve Garcia
Reply to  Steve Garcia
July 30, 2015 1:08 pm

SH –
You say, “Asteroids with a one km diameter strike earth every 500,000 years on average. Larger collisions, of five-km objects, happen approximately once in twenty million years. The last known impact by an object of 10 km or more in diameter was the K-T (or P) extinction event 66 million years ago.”
I can put up numbers, too… A bit on the evolution of the estimates of frequencies of impacts on Earth:
Gerrit L. Verschuur, in “Impact!: The Threat of Comets and Asteroids (p. 157)” wrote:
“…Specific odds were offered by Sir Richard Gregory in 1893: “about once in about twenty million years.” In 1897 David Todd offered an estimate of an impact every 15 million years, but even if the earth should pass through the head of a comet, it might bring universal death to nearly all forms of animal life. The famous textbook of Russell, Dugan, and Stewart in 1926 stated flatly that comet collisions would happen once in 80 million years.” [Note that no size was given. These were blanket statements about ALL comets.]
“…Representing the Lone Ranger point of view, Clark Chapman and David Morrison published their odds in Nature in January 1994. In “Impacts on the Earth by Asteroids and Comets: Assessing the Hazard,” they concluded that the chance that a large (2-kilometer diameter) object will slam into the planet and terminate civilization during the next century is I in 10,000. (pg 159)”
Note that this is the same David Morrison who is the director of NASA, and this was the same year that Shoemaker-Levy 9 broke into 20 large fragments which slammed into Jupiter over the course of several days in July of that year.
Note also that until the Shoemakers and Levy found SL-9, NO astronomers or anyone at NASA thought that they would ever in their lives see a comet hit a planet. And, to add insult to injury, TWO other comets have since 1994 been seen to hit Jupiter.
So much for the estimations of frequencies of comet strikes on planets? Maybe, but we raren’t done yet.
Continuing. . .
“In July 1994 an interesting article appeared in Scientific American on what was learned from the Apollo moon landings. The author, G. Jeffrey Taylor, a geophysicist physicist at the University of Hawaii in Honolulu, pointed our that for every impact crater you see on the moon there would be 20 expected on the earth, because of the earth’s larger size. He added that Frederick Horz of the Johnson Space Center estimates that there are 5000 craters on the moon larger than 5 kilometers across which were produced in the past 600 million years. Putting these numbers together implies that half-kilometer objects, which are potentially civilization-destroying, are expected on average every 6,000 years. This rate is consistent with the claims made by the Tollmanns (chapter 8). If earth is hit by a 0.5-kilometer object every 6,000 years, roughly four out of five would be expected to land in the oceans, which means it is very likely that a major flood event would have occurred at least once in the past 10,000 years. (p. 162).”
(Don’t tell the Creationists!)
“While researching old books and technical articles for this chapter, I noticed something fascinating that illustrates how our conception of what the future holds depends so intimately on our knowledge base. In two centuries, the typical estimated time between comet impacts (from old books) to impacts capable of producing global catastrophe (from new research) has decreased from once every 281 million years (which held for most of the 19th century) to about once ever 5 to 10,000 years in the past year.
“…Compared to estimates made in the past century, one thing has changed in recent years. The NEAs have entered the picture and therefore the odds of impact have shortened dramatically. Around the end of the nineteenth century the odds had shortened to once every 10 million years or so, which held until the early 1980s when 100,000 years between civilization-destroying impacts began to surface. That change happened because of the sudden increase in information about NEAs, crater statistics, and past mass-extinction events. A spate of at least nine estimates appeared in early 1995, four of which independently set the interval between such collisions at close to 5,000 years. (p. 164)”
On another tack ——– From we have this:
“…Dr. Brian Marsden, director of the Minor Planet Center in Cambridge, Massachusetts, which catalogues all newly discovered near-Earth objects and tries to accurately determine their orbits…
“… In 1998, the center listed 10,000 objects. Two years later, the number has risen to 15,000. Most are objects traveling harmlessly in the asteroid belts between Mars and Jupiter, and more are being discovered everyday…
“…A smaller subgroup, called Potentially Hazardous Asteroids, includes 249 objects that are one-tenth of one mile or larger, and pass within five million miles of the Earth. Last year, about 100 new objects were added to this list.
“Most of these objects are not a danger,” says Dr. Marsden. “But in the last two years, there have been five objects with a significant impact possibility during the next half-century.” Intense efforts are underway to determine the orbits of these objects. All but one has been ruled safe. This one object, which appeared in 1998, but vanished before an orbit could be determined, is listed as a potential threat to the Earth.”
So, the number of known threats becomes higher. IN one year it went up about 40% – and that ws before WISE mission began looking seriously.
At about the end of 1980 9,425 asteroids were known. By 1985 that had grown to 12,214. In 1990 it wsa 26,748. BY 2000 it had grown to 123,114. Then in 2005 the count went to 343,671. In 2010 it was 548,914. In 2013 it had grown to 588,992. Those are all now known, numbered and tagged. The number went up by 62-fold.
These absolute numbers don’t mean that the danger to Earth has increased or decreased. We are not 62.5 times more much in danger than 35 years ago. We just have more information.
But we DO need to be aware that old estimates, based on old numbers, cannot fly. Estimates need to be based on the numbers we DO know about – and WHAT we know about them. If we see that 588,991 of those will never be a threat, the ONE that is left is not much of a threat.
But with the NEAs/NEOs numbers up several-fold since 1980, we DO now know the threat more than ever, and the odds are not once in 500,000 years anymore.
SH, it looks like your numbers are based on information from probably 40-50 years ago.

Steve Garcia
Reply to  Steve Garcia
July 30, 2015 1:15 pm

SH –
BTW, don’t take that lsat comment as me doing the alarmism thing. YOU brought up some old numbers on the estimations about frequency, and I just had to update them.
The Verschuur book dates all the way back to 1996, so even HIS numbers are ancient.
If the risk is one 1/2 km object every 6,000 years, even based on 1996 information, then something big hitting 13,000 years ago is a bit of a big gap since then. Are we at risk now? HELLIFIKNOW. I think we are doing the right things – collecting as much information as possible.
I am much less interested in any new ones coming along. If they come and wipe us out, they do. I’ve gotta die sometime. Who knows? That would be an interesting way to go. For now, I am mainly interested in seeing what they turn up about the one at the YDB. Comet? Meteor? It doesn’t matter, if it does its damage, it does its damage.

Reply to  Steve Garcia
July 30, 2015 1:16 pm

Steve, also note, that as time marches onward, our observational equipment improves, and we are getting close to the point where we just might be able to observe the impactor before it strikes. Hopefully we might even be able to do something about it too.

Sturgis Hooper
Reply to  Steve Garcia
July 30, 2015 1:21 pm

Wrong again, as always. Those are the best recent estimates from my colleagues still actively working on the relevant issues.
They are the same estimates used by NASA in assessing risk.

Bloke down the pub
July 27, 2015 2:52 pm

Best guess as to where this comet impacted, or whether it even survived to reach ground level?

Reply to  Bloke down the pub
July 27, 2015 3:21 pm

This is a really good way to start a flame war. The Y-D impact theory is about as contentious as you get. Two sites I have seen proposed are Hudson Bay and the Great Lakes. According to one group, you need an impact that dumps material on a site in Georgia (?), or thereabouts. Southward aimed impacts from the two northern sites would do that. Even finding the tektites and nanodiamonds has been contentious.
A: We found nanodiamonds!
B: We looked, found nothing.
A: You looked in the wrong layer.
B: Did Not!
A: Did So!
Popcorn Time.

Leonard Lane
Reply to  TonyL
July 27, 2015 10:27 pm

TonyL. Sites and dates of comet or asteroid impacts on earth are contentious in themselves, then to further stretch and say they caused the Y-D cooling. Much speculation and very short on quantitative data. I see no consideration of alternative hypotheses.

Steve Garcia
Reply to  TonyL
July 27, 2015 11:31 pm

Leonard Lane – Actually, when Richard Firestone first began finding out about this evidence, a comet was not in his mind at ALL. One of his early ideas was that a supernova had blasted Earth with energy and particles.
And WHY was he even looking for anything? One of his fields of research is Carbon-14. We all know here that the C14 calibration curve turned out to not be a straight line. It had dips and non-dips in it. He was trying to understand some of those.
It isn’t science as in peer-reviewed papers, but you might find Firestone’s book, “The Cycle of Cosmic Catastrophes” to be an informative book, not only about this event, but how scientists work in the field (NOT Firestone’s normal venue).

Jim payette
Reply to  TonyL
July 29, 2015 11:10 pm

There are the Carolina bays – tearshaped pond like structures oriented as coming from a north west direction from N Florida up into Virgina and Md. They are poorly understood as no terrestial terraforming actions can explain them. Dating them is contentious but some people do date them as early as the Younger Dryas (most dating says much older). Some of the dating controversy can be explained if the strata in which they are made was ejecta from an impact elsewhere and the bays made by ice impacts. There could also be much smaller amounts of material from the extraterrestial object – most likely a comet exploding somewhere around the Great Lakes. It must be noted that none of the photos of comets taken by flybys show anything resembling an iceball – they all look the like small asteroids to me. The evidence seems to say that comets, meteors, and asteroids are more alike than different – their obits being the biggest difference.

Reply to  Bloke down the pub
July 29, 2015 2:09 am

One of the largest precious metals mines is in Canada somewhere near Quebec I think. The thesis is that the space rock impacted mile thick ice there (sending a tidal wave of ice slush into siberian mammoths…) and leaving the metals in the future mine. Ejecta made secondary impacts in the Carolinas that have tails pointing back to the impact in Canada.
Since it was mostly ice, no solid crater but lots of “scour”. And enough air burst and impact to make the glasses and diamonds and such. Also large objects often break up and arrive in chunks. See Jupiter and Shoemaker Levy 9 (sp?).
IIRC, Enke was breaking up then and parts of the proto “it” have the right timing to be this impact. We still get Taurid meteor showers from it…

Steve Garcia
Reply to  E.M.Smith
July 30, 2015 1:18 am

E.M. – You got me thinking on this now…
The crater that is the basis for the mine is assigned a date of 1.8 billion years ago. That is a problem, but if an error can be shown, or sufficient reasons to challenge that…
Taurids? They are part of the overall.
Two researchers – Michael Davias of and Tim Harris, a rocket scientist, have worked up a connection to the Australian Tektite Field and also with the Carolina bays. They put it at 780,000 years ago, which is also the time of the Brunhes–Matuyama geomagnetic reversal.
They are my friends, but I’d like to see their date be wrong. I am thinking in the time after the Encke Progenitor breakup – i.e., the last 30,000 years or so. I have trouble with the Carolina bays being so old, geomorphologically speaking. Tim and Michael think they are quite robust. I don’t think THAT robust.

July 27, 2015 3:00 pm

They are thinking it hit mainly in the Carolinas of the USA.
And speculation that this is what killed off a number of megafauna mainly in the North American continent coupled with the arrival of humans with their wolf/dogs back then meant annihilation for a number of megafauna that never saw either ape-type hunters or their puppy dogs before 12,000 years ago.

Reply to  emsnews
July 27, 2015 4:21 pm

And the saber toothed cats and dyer wolves lunched on the dogs! My personal vote is for the introduction of some sort of pathogen. Think of it the way small pox wiped out native Americans.

Reply to  fossilsage
July 27, 2015 11:35 pm

Sorry but Canis lupus simply out competed both the smilodons and C. dirus. It is not a choosey like its competition was.

Steve Garcia
Reply to  fossilsage
July 27, 2015 11:40 pm

fossilsage – Oops! Your userID suggests you know about such things, but you slipped.
It is D-I-R-E wolves, not “dyre wolves”.

Reply to  Steve Garcia
July 28, 2015 9:01 am

well that’s the way they spelled it back in the old days!

Reply to  emsnews
July 27, 2015 7:25 pm

Actually one of the casualties were the Clovis humans that were already here.

Reply to  denniswingo
July 27, 2015 11:25 pm

The Clovis humans were not casualties. The Clovis culture just morphed into something different and the people moved on because of the faunal shift. Paleo Americans moved around a lot. A journey of a couple thousand miles was trivial.

Steve Garcia
Reply to  denniswingo
July 28, 2015 12:07 am

Correct. denniswingo. After right about 12,800 yeas ago, poof! No more Clovis artifacts. Actually, though, at the Anzick site in Montana, a recent study concluded that the “sub-adult” bones found were Clovis and the newspapers had a field day talking about them being able to do a DNA genome of a Clovis man, dated to about 12,200 years ago (from my memory) – centuries after the YDB and also centuries after the latest Clovis dates previously determined.. However, it took me only about 15 minutes of googling to find out that the human remains found at Anzick were NOT able to be tied to the large Clovis tool assemblage, in the layers. Part of that problem was that heavy equipment is what uncovered the whole thing, and before anyone new it, the layers had been disturbed, removing ANY clear chance to connect the bones with the stones. And since the site was ALSO later a bison over-the-cliff kill site (MANY bison bones were found), the site was obviously used by humans later on. So, the site has had a LONG history of human presence. YES, Clovis artifacts were found there.
How the artifacts got there and why no one knows. A 1996 study doubted that it was a “cache” location for hunters. Some think it was a workshop for producing them. If Clovis did die out centuries earlier, it poses a problem, but not an intractable one. Stones, as every archaeologists knows, last a long time. Archaeology is very much BUILT on the fact that stones last a long time. If trade existed at the time of Clovis (and that is not out of the question), then anyone who traded with Clovis could have taken the artifacts anywhere. It did not have to be Clovis people to have Clovis artifacts. We have Japanese cars, and that doesn’t make us Japanese.

Reply to  emsnews
July 27, 2015 11:37 pm

The wolves came of there own accord. The dogs that were brought, were of a pariah type, e.g. the Carolina Dog, not lupines.

Steve P
Reply to  DesertYote
July 28, 2015 9:47 am

Native americans ate dogs.

Steve Garcia
Reply to  emsnews
July 27, 2015 11:38 pm

NO, emsnews, they do NOT think that a comet hit in the Carolinas. You are conflating an early (later deleted) idea that they had, that the ejecta from a Great Lake AREA ice sheet impact caused the Carolina bays. II reiterate: They have long ago decided that this part wouldn’t fly.
YES, to the still-on-the-table idea that the comet impact (if it still holds true) was perhaps connected. THIS is something that they MAY connect in the future – possibly in the same way as this paper, with Bayesian statistical analysis. But at the present time it is only a possible future research topic. Certainly by connecting the OTHER, lab results – which are C-14 dated and dated in other ways – in this current study they have tied OTHER things together in time. That was a necessary step. Applying it to extinctions would be a proper thing to do – IN ITS TIME. They are careful scientists and they are being careful to do the proper analyses at their proper times, in the proper sequence.

Phil R
Reply to  emsnews
July 28, 2015 11:17 am

Just curious because I live in SE USA (Virginia), near the Carolinas. Any thoughts on where it was supposed to impact? I ask because 12,000 years +/- is very recent, geologically speaking, and I would think that the remnants from a large impact only 12,000 years ago would be fairly obvious.

Steve Garcia
Reply to  Phil R
July 29, 2015 8:41 am

For various reasons, “where it was supposed to impact” was on the Laurentide ice sheet somewhere near its southern edge in the general region of the Great Lakes – but that is a very general location and very tentative.
Since there IS no “fairly obvious” crater, that makes the ice sheet impact scenario almost a must. Peter Schultz does hyper-velocity experiments, and his work with scaled down impacts onto ice covering simulated ground material showed that the ice attenuates the impact energy, while absorbing much of the energy and dissipating it. That doesn’t mean that no ejecta materials were thrown out. No one knows for sure what the specifics were. So far they have mostly tried to solidify their evidence at thee small scale, nanodiamonds and carbon spherules and other materials that normally are interpreted as impact materials. One step at a time. First make sure the materials are correct – then go on to extrapolate that out.

Star Craving Engineer
Reply to  Phil R
July 29, 2015 8:42 am

Phil R,
Some current research on the Carolina bays can be found at
The impact site they’re presently considering is described at
and the associated links. The cintos group believes that the bays were made by the ejecta from a huge impact some 800,000 years ago, and that they’re unrelated to the 12,800ya hypothesized Younger Dryas Boundary impactor. Their analysis of trajectories is impressive, I’m not so sure about their dating.

Steve Garcia
Reply to  Phil R
July 29, 2015 10:40 pm

Star Craving Engineer –
Yeah, Cintos has some interesting stuff there. He’s also mapped all of the Carolina bays using Lidar to find and measure them.
You might want to know that he and a co-researcher have tied that all to the 780,000 impact that created the Australian Tektite Field.

July 27, 2015 3:06 pm

“… the production of which can be explained only by cosmic impact …”
In the same way that global warming can be explained only by man’s CO2.

Reply to  Tony
July 27, 2015 3:34 pm

Hey, I get to reply to myself, almost. Or my almost self.
Actually, tektite and nanodiamond formation only by impact is well accepted by the scientific community, across disciplines. You can make them in the lab for comparison. I got a feeling this thread is going to get interesting.

Reply to  TonyL
July 27, 2015 3:59 pm

Correctly described tektites, yes. Ditto shocked quarz, of which Kennet finds precisely none (a remarkably pure comet?). High temp,cosmic impact. Sure.
ANY carbon allotrope (nanodiamonds, buckeyballs, nanotubes, graphenes, agglomerated spherules) are produced in any carbon combustion process. Quantities vary with temperature and fuel source. But ordinary candle soot suffices. Nanodiamonds scrubbed off the Cistene Chapel restoration. The horror!

Reply to  TonyL
July 28, 2015 1:12 am

Nano-diamonds can be created anywhere in space from free floating carbon by supernovea explosions shock-wave, then at a later stage attracted by gravity of a passing asteroid eventually ending in the earth’s atmosphere during the impact.

July 27, 2015 3:32 pm

I think it was a battle star first because it is more plausible, and second, it requires only imagination, not models. And since no climate alarmist scientists were involved in inventing this solution there is a much higher probability of truth. Finally, battle stars are almost 100% titanium with a tiny percentage of unobtanium and unlikelium, and the latter two have never been found which would be expected. Solved.
And here’s the obligatory /snark for the net nannies out there.

Reply to  dp
July 27, 2015 4:07 pm

“Pray that I do not alter your climate further….”

July 27, 2015 3:33 pm

Where is the layer of iridium?

Reply to  Gums
July 27, 2015 3:39 pm

K-T (or C-T, K-pg) Boundary. 66 million years ago. Closed down the original Jurassic Park. You know the rest.

Robert of Ottawa
Reply to  TonyL
July 27, 2015 3:53 pm

So why platinum this time?

michael hart
Reply to  TonyL
July 27, 2015 4:06 pm

That was my thought. What is so special about platinum in this case. Why not other elements too?

Reply to  TonyL
July 27, 2015 4:15 pm

@ Robert
Apparently, impacting asteroids are like fussy women who will not wear the same outfit to social events twice. They need a new outfit every time.
One could speculate endlessly about the physical/chemical processes which fractionate the elements and produce space rocks with such different compositions.

Reply to  TonyL
July 27, 2015 7:26 pm

Platinum is exceedingly rare in the Earth’s crust, almost all that we have has a meteoric source. Thus if there is a layer of any PGM in a certain layer it is almost certainly diagnostic of an extraterrestrial impact of an M or CC or cometary body

Steve Garcia
Reply to  Gums
July 28, 2015 12:12 am

ALL inbound objects don’t have iridium. Just like all meteorites aren’t iron or nickel. Meteorites come in several classifications. Look it up. And if they aren’t all made up of the same things when we find meteorites, then WHY would all impacts be exactly the same?
Sorry. Some have platinum. Platimum spikes at the YDB time? Yes. It’s in the journal papers. And in the Greenland ice sheet. And right at the time of the YDB. Funny thing, that. Look it up.

July 27, 2015 3:39 pm

Kennet just won’t let this previously falsified hypothesis go. It was thoroughly debunked by radiocarbon dating of over 20 of his supposed sites around NH, (ASU, IIRC 2013) so here he selectively revises the radiocarbon dates. Rather like Karl and the pause.
And the carbon spherules/nanodiamonds? From forest fires. Every candle ever lit produces them. Another paper that denunked the ‘high temp impact’ claim. Carbon soot is amazing stuff.
I was going to write an essay for the book,on this. Months of research about ‘abrupt’ tipping points in nonlinear dynamic systems. Scrapped. Willis Eschenbach is right in general about thermoregulation. YD is not a disproof.
The Younger Dryas onset is fairly well established science. Retreating Laurentide ice sheet finally allowed large paleolake Agassiz (meltwater south) to punch through what is now the St. Lawrence seaway. The massive and very abrupt freshwater pulse interupted the North Atlantic thermohaline circulation. There are even massive geological water scours that show how violent the event was.
What is interesting and NOT well understood is why the YD ended as abruptly as it started? That is where the research bucks should go. No comet hypothesis about YD end…yet. Although one could make up a story that an undetectable ocean comet impact suddenly restarted thermohaline circulation. It would have had to be an equatorial Atlantic impact, heated water pulse flowing poleward, and all that. Maybe the Mayan calendar holds some clues…

Reply to  ristvan
July 27, 2015 5:21 pm

Well, it’s certainty that over last 100,000 year there has been numerous impacts- and even the rarer cometary impacts.
The last known largest impact, was Tunguska event, which was small compared to larger one we would see over a 100,000 year period. Wiki, Tunguska event:
“Estimates of the energy of the blast range from as low as three to as high as 30 megatons of TNT (between 13 and 130 PJ).Most likely it was between 10 and 15 megatons of TNT (42 and 63 PJ),[9] and if so, the energy of the explosion was about 1,000 times greater than that of the atomic bomb dropped on Hiroshima, Japan; roughly equal to that of the United States’ Castle Bravo ground-based thermonuclear test detonation on March 1, 1954; and about two-fifths that of the Soviet Union’s later Tsar Bomba (the largest nuclear weapon ever detonated) ”
So in terms of a climatic effect we can dismiss Tsar Bomba type impactor or smaller, as we dismiss Tunguska event as having any effect on global climate.
But it possible that impactor with more explosive power than Tsar Bomba, which occurred many times over last 100,000 years, have had no effect.
Now if take a really large impactor like one than killed the dinosaurs 65 million years ago, there should no doubt such large impactor would affect global climate. Or wiki:
“The Chicxulub impactor had an estimated diameter of 10 km (6.2 mi) and delivered an estimated energy equivalent of 100 teratons of TNT (4.2×1023 J).[21] By contrast, the most powerful man-made explosive device ever detonated, the Tsar Bomba, had a yield of only 50 megatons of TNT (2.1×1017 J), making the Chicxulub impact 2 million times more powerful. Even the most energetic known volcanic eruption, which released an estimated energy equivalent of approximately 240 gigatons of TNT (1.0×1021 J) and created the La Garita Caldera, delivered only 0.24% of the energy of the Chicxulub impact.”
So, Tunguska event was less than Tsar Bomba and Chicxulub impactor was 2 million times Tsar Bomba
So of range of starting from 50 to 10,000 Tsar Bomba, would they have any effect, and rather than just the explosive power, it seems it could matter where and when they hit. And is possible that the energy of a nuclear war, would not have any climatic effect?

Leo Smith
Reply to  gbaikie
July 28, 2015 2:47 am

Yerrsss. I too have been looking at the energies associated with natural and man made events: The ‘end of civilisation on account of nuclear war’ simply doesn’t fly .
I have assumed it was yet another ‘convenient lie’ to scare populations into putting pressure on governments. Part of the cold war black propaganda.

Leonard Lane
Reply to  ristvan
July 27, 2015 10:35 pm

Thanks ristvan. Hmm the end of the Y-D must have been caused by another comet that caused heating. Maybe it was mostly CO2? Or maybe anti-platinum. Or maybe the Y-D begin and end were from natural processes in our oceans and atmospheres.

Steve Garcia
Reply to  ristvan
July 28, 2015 12:17 am

Ristvan, obviously you side with the skeptics there on the YDIH, too. You have that right, to do that. But while you are claiming that the YDB impact scenario has been “falsified”, you just MIGHT want to go and look up the rebuttal papers and letters in the journals to see how the YDB people shot down damned hear every one of the skeptics’ points. And the few that wee not shot down were extremely minor points.
The YD Impact Hypothesis stands UN-FALSIFIED at this time.
If you are going to pretend to be scientific, you should read up on ALL the claims – even the claims of falsification. I am not even going to point you at the rebuttals. You are so smart, go out and find them yourself.

Samuel C. Cogar
Reply to  ristvan
July 28, 2015 8:02 am

The Younger Dryas onset is fairly well established science.

If one assumes that this temperature proxy graph is anywhere close to being correct …… then one has to ask themselves …..
“Was the Younger Dryas a sudden-like cooling event (13.5Kt o12K BP) …. or was it just the continuation of a pre-14.5K BP cool period …. that was interrupted by a temperature “spike” or increase?”comment image
That graph implies that the temperature cooled off kinda gradual like to become the Younger Dryas Period …. and then rebounded quite quickly to “mark” the start of the Holocene Optimum.
A 2,000+- years of a gradual “cool-off” ….. instigated by a comet/astroid/metero “strike” has my curiosity aroused.

Steve P
Reply to  Samuel C. Cogar
July 28, 2015 9:55 am

What caused the significant spike 15,000 years ago, about 3000 years before the YD? Was this the warming that unleased the Kankakee Torrent?

Steve Garcia
Reply to  Samuel C. Cogar
July 28, 2015 1:39 pm

I find that graph quite interesting, the snow accumulation trace especially. For those at WUWT who haven’t heard it said, “Snow doesn’t accumulate when it is too cold.”. LOOK at how little snow accumulated when the temps were down at -50°C – and how MUCH accumulated when the temps rose above -35°C.
In fact, that .22-.25 meters/year of snow accumulation after 10,000 years ago adds up to something like maybe 2200 meters of snow accumulated since the end of the YD. Make it 2000 meters – to be conservative? 2000 meters is nearly 6600 feet. I DO assume (maybe wrongly) that the “accumulation” is as found in the ice cores, compacted and all.
From Britannica:
“The northern dome, located in east-central Greenland and reaching more than 10,000 feet (3,000 m) above sea level, is the area of maximum thickness of the ice sheet.”
Wiki gives the thickness as 2000-3000 meters.
So, are we then to gather that the Greenland ice sheet was only about 800 meters before the end other YD? That is kind of what it looks like…
I don’t know! I am just asking!

Steve Garcia
Reply to  Samuel C. Cogar
July 29, 2015 1:53 am

Steve P – Good question. The answer in terms of names is the OLDER Dryas. It came along and stopped the warming of the Bølling warm period. It was very short, and was followed by the Allerød warm period – which was the one in effect at the onset of the YOUNGER Dryas.
In terms of WHAT cause that cool-down, heck, no one knows WHAT mechanism or process did ANY of it. There is an orthodoxy which explains it according to gradualism and internal “forcings”. But there are many aspects that the orthodoxy and its favored processes do not handle well (fail to explain), so the overall is that no one really knows.

Reply to  Samuel C. Cogar
July 29, 2015 2:19 am

Remember that compacted ice is about 1/10 the thickness of the fluffy snow that fell…

Samuel C. Cogar
Reply to  Samuel C. Cogar
July 29, 2015 8:24 am

Steve Garcia – July 28, 2015 at 1:39 pm

“The northern dome, located in east-central Greenland and reaching more than 10,000 feet (3,000 m) above sea level, is the area of maximum thickness of the ice sheet.”
Wiki gives the thickness as 2000-3000 meters.
So, are we then to gather that the Greenland ice sheet was only about 800 meters before the end other YD (@12K BP)? That is kind of what it looks like…
I don’t know! I am just asking!

Steve G,
The way I figure it is that they “don’t-have-a-clue” as to how thick the Greenland ice sheet was before the end of the YD, …. or for that matter, ……. before the onset of the Holocene Climate Optimum @ 10.5K BP as noted on this proxy graph, to wit:comment image
The following study confirms that there surely was or should have been ….. 6,000+- years of “serious melting” of the Greenland glaciers, to wit:

Holocene Treeline History and Climate Change Across Northern Eurasia
Radiocarbon-dated macrofossils are used to document Holocene treeline history across northern Russia (including Siberia). Boreal forest development in this region commenced by 10,000 yr B.P. Over most of Russia, forest advanced to or near the current arctic coastline between 9000 and 7000 yr B.P. and retreated to its present position by between 4000 and 3000 yr B.P. Forest establishment and retreat was roughly synchronous across most of northern Russia.
During the period of maximum forest extension, the mean July temperatures along the northern coastline of Russia may have been 2.5° to 7.0°C warmer than modern. The development of forest and expansion of treeline likely reflects a number of complimentary environmental conditions, including heightened summer insolation, the demise of Eurasian ice sheets, reduced sea-ice cover, greater continentality with eustatically lower sea level, and extreme Arctic penetration of warm North Atlantic waters. The late Holocene retreat of Eurasian treeline coincides with declining summer insolation, cooling arctic waters, and neoglaciation.
Excerpted from:

So my question is, ….. how many feet of ice melted off the “top” of the Greenland glaciers?

Reply to  ristvan
July 29, 2015 2:33 am

In this posting I cite an article that finds the Gulf Stream is metastable at the glacial times and stable during the interglacial
That means thing switch strongly 20000 years ago, but not 5000 years ago.
In that context, a warm swap can be knocked over to a cold state and latch up for 1000 years till another push swaps it back to warm. Eventually orbital changes have us latch up in a stable interglacial warm, until orbit changes put us back at metastable heat levels.
We are very near metastable heating now and a good cold spike would have decent odds of sticking…. then over the next 90000 years the climate is prone to very strong swings… multiple C swings… without a single stable state.

Paul Westhaver
July 27, 2015 3:46 pm

I like this kind of speculation. It seems like a reasonable, inspired hypothesis to think that the ice age was preceded and caused by a collision between earth and an extraterrestrial object. I don’t know much about this kind of collision mechanics and the evidence it would leave, but I would like to know:
What was the earth’s climate like at the last moment BEFORE the impact, should there have been one.

Steve Garcia
Reply to  Paul Westhaver
July 28, 2015 12:24 am

Paul – Acctually a very good question.
And the answer is that BRIEFLY the climate was very close to today’s climate. And then, after the Younger Dryas mini ice age that lasted 1300 years, the climate went into a similar climate to today again.
The Last Glacial Maximum (LGM) ended about 22,000 years ago, and between then and the YDB at 12,800 years ago, there were two warm periods separrated by a bvery short cold period. The cold period was the FIRST Younger Dryas, the Older Younger Dryas. It separated the Bolling warm period from the Allerod warm period, which is the one that the Younger Dryas ended so abruptly.
BTW, all of those periods were discovered and named by biologist types who recognized the changes in flora in Scandinavia. The dryas is a type of arctic flowering plant.

July 27, 2015 3:48 pm

Whew! If CO2 didn’t cause it, then it is always due to some kind of impact, isn’t it? What if the sudden catastrophe was due to something other than an impact? I’d like to think that these researchers could come up with more creative theories than comet impacts. Maybe it’s time to think outside the box.

Robert of Ottawa
Reply to  Jbird
July 27, 2015 3:58 pm

See Restvan above
Retreating Laurentide ice sheet finally allowed large paleolake Agassiz (meltwater south) to punch through what is now the St. Lawrence seaway. T

Jim payette
Reply to  Robert of Ottawa
July 29, 2015 11:27 pm

Newer research says that did not happen. There was a big lake it just slowly evaporated when water stopped draining into it. No evidence shows there was giant punch through.

Leonard Lane
Reply to  Jbird
July 27, 2015 10:38 pm

Lots of comet impact theories but no references to Velikosky.

Reply to  Leonard Lane
July 28, 2015 5:41 am

His story of SW Native Americans seeing a big fire in the sky to the NE, always comes to mind.

July 27, 2015 3:49 pm

No, no and NO! The YD was not caused by a cosmic impact and was just one of many abrupt climate changes between 20,000 and 10,000 years ago.
The ice dynamic was such during this time period that only small amounts of forcing were needed to send the climate into another climate regime.

Steve Garcia
Reply to  Salvatore Del Prete
July 28, 2015 12:35 am

Man, you are talking to the wrong crowd, talking about small changes making LARGE climate shifts.
You are repeating the orthodox paradigm. This hypothesis challenges the orthodoxy, so why wouldn’t the orthodoxy scream bloody murder, that the orthodoxy is being challenged?
There are correct, that in the Greenland ice cores GISP2 and GRIP, especially, show 18-oxygen PROXIES for temperature – and that those PROXIES seem to show that the temperatures were going UP and DOWN and UP and DOWN – by as much as 14°C – a HUGE amount. On WUWT here, again, you will find resistance to the reliability of proxies.
Climate change on that order, so many times – and “it just happened” each time, right? Oh, really? All by its lonesome? No industrial CO2 emissions? No internal combustion engines? No Chinese economic miracles?
Blaming it on “the ice dynamic was such” is like saying, “It’s a MIRACLE!” or, “It’s just a coincidence”. What does ice dynamic even MEAN? And what does “as such” mean”? A waffle word phrase. Waffling because YOU don’t know what caused them, either. No one does.
And we WON’T, not for a long time. We don’t have enough facts to know. And when someone comes along and finds FACTS, what do you do? Dig your heels in and hunker down behind the protection of the orthodoxy. Have you even READ any of the journal papers? I am betting the answer is NO.
NO, NO, and NO!

Reply to  Steve Garcia
July 28, 2015 9:10 am

Steve Garcia
l believe l understand how the weather patterns could cause such big swings in Greenland temps.
Persistent blocking highs between Greenland and northern Europe would have pushed a lot of warmer air from the south up across Greenland. Which would have lead to a noticeable warmer of Greenland.

Steve Garcia
Reply to  Steve Garcia
July 29, 2015 12:21 am

taxed – A good, reasonable insight. The difficulty, though, is that one would need the blocking high to be stable and more or less stationary for close to 1400-1500 years, on a pretty much regular schedule. We might have trouble convincing anyone that that could happen, with known climate evidence from the past and meteorological evidence of what happens now.
And the alternate blocking highs would have to be pretty much the same, each time it shifted that way. Doubtful? I think so, but I could be wrong.
The up-down shifts were amazingly regular – for which NO known terrestrial process or mechanism could be ascertained. AND THEY DID LOOK. So, basically, for now they’ve thrown their hands up as far as terrestrial processes are concerned. They do NOT, however, entertain the idea of an ET cause, which one would expect them to do.

July 27, 2015 4:00 pm

The explanation below is for the Little Ice Age and I think it can be applied to the YD, despite the fact Milankovitch Cycles were not that favorable at that time , but the Ice Dynamic for sure was and that changed the whole dynamic of the playing field and is the factor which made abrupt climatic changes to happen so frequently 20000 to 10000 years ago.
The YD was just one of many abrupt climatic changes during that time period.
This theory combined with my input for how the Little Ice Age may have started can also be applied to the YD, with the big difference being the all important Ice Dynamic at the time of the YD ,which made the climate more vulnerable to change with much less forcing.
This article is good but it needs to emphasize the prolonged minimum solar /volcanic climate connection( which it does not mention ), and other prolonged minimum solar climate connections such as an increase in galactic cosmic rays more clouds, a more meridional atmospheric circulation due to ozone distribution/concentration changes (which it does not do ) which all lead to cooler temperatures and more extremes .
In addition they do not factor the relative strength of the earth’s magnetic field.
When this is added to the context of this article I think one has a comprehensive explanation as to how the start of the Little Ice Age following the Medieval Warm Period may have taken place and how like then (around 1275 AD) is similar to today with perhaps a similar result taken place going forward from this point in time.

I want to add the Wolf Solar Minimum went from 1280-1350 AD ,followed by the Sporer Minimum from 1450-1550 AD.
This Wolf Minimum corresponding to the onset of the Little Ice Age.
John Casey the head of the Space and Science Center, has shown through the data a prolonged minimum solar event/major volcanic eruption correlation.
Today, I say again is very similar to 1275 AD. If prolonged minimum solar conditions become entrenched (similar to the Wolf Minimum) accompanied by Major Volcanic Activity I say a Little Ice Age will once again be in the making.
Milankovitch Cycles still favoring cold N.H. summers if not more so then during the last Little Ice Age , while the Geo Magnetic Field is weaker in contrast to the last Little Ice Age.
I would not be surprised if the next Little Ice Age comes about if the prolonged solar minimum expectations are realized in full.

Steve Garcia
Reply to  Salvatore Del Prete
July 28, 2015 12:39 am

Milankovitch cycles are totally inadequate to bring about sudden climate change – much less 14°C in a year or two, as indicated in the Greenland ice cores.. The Milankovitch cycle changes are over 100s of thousands of years, making the changes SO incremental as to seem standing still. How can Milankovitch cycles make changes in a few years and then make NEW changes in the same up or down part of the Milankovitch cycles. The idea is preposterous. It’s as silly as warmists claiming that 0.7°C is even noticeable by humans, much less a climate catastrophe.

Reply to  Steve Garcia
July 28, 2015 8:05 am

You did not listen to what I said Steve. I said in the above post that Milankovitch Cycles were NOT favorable to support the YD cold era.
I said however the Ice Dynamic at that time was.

Reply to  Steve Garcia
July 28, 2015 9:20 am

A persistent blocking high in the northern Atlantic can lead to a large increase in temps over Greenland in well within the space of a year. Because a blocking high in the right place can push the temps along the western coast of Greenland up to 12c in Nov/Dec.

July 27, 2015 4:05 pm

I had been assured that the YD was caused by a slowing of the Gulf Stream due to glacial meltwater and that we were in for a repeat soon. Plus it was in the movie The Day After Tomorrow.

Steve Garcia
Reply to  TJA
July 28, 2015 12:41 am

That was the hypothesis based on Wally Broecker’s oceanic conveyor, and later on Broecker himself rescinded his support of the idea. The meltwater pulse was impossible at that time, because the ice was too far south still. The meltwater pulse, if it ever happened, could not have gone out the St Lawrence from glacial Lake Agassiz. The data said no, and Broecker agreed.

Reply to  Steve Garcia
July 28, 2015 9:00 am

Steve Garcia

The meltwater pulse was impossible at that time, because the ice was too far south still. The meltwater pulse, if it ever happened, could not have gone out the St Lawrence from glacial Lake Agassiz.

An impact in that area might have destroyed enough of the southern ice-sheet to allow some/all drainage into the St Lawrence at some point. So a possibility is a YD initiated by an impact & prolonged by a subsequent massive dump of freshwater into the N Atlantic?

Sturgis Hooper
Reply to  Steve Garcia
July 28, 2015 9:11 am

Meltwater also enters the Gulf of Mexico and Arctic during LIS deglaciations, as well as via the St. Lawrence.
Meltwater input from the Laurentide Ice Sheet (LIS) has often been invoked as a
cause of proximal sea surface temperature (SST) and salinity change in the North
Atlantic and of regional to global climate change via its influence on the Atlantic
meridional overturning circulation (AMOC). Here we review the evidence for
meltwater inflow to the Gulf of Mexico and its reduction relative to the onset of
the Younger Dryas, compare inferred meltwater inflow during marine isotope stage
3 (MIS 3), and thereby assess the role of LIS meltwater routing as a trigger of
abrupt climate change. We present published and new Mg/Ca and δ18O data on the
planktic foraminifer Globigerinoides ruber from four northern Gulf of Mexico
sediment cores that provide detailed records of SST and δ18O of seawater (δ18Osw)
for most of the last glacial cycle (48–8 ka). These results generally support models
that suggest meltwater rerouting away from the Gulf of Mexico and directly to the
North Atlantic may have caused Younger Dryas cooling via AMOC reduction.
Alternatively, southern meltwater input may simply have been reduced during the
Younger Dryas. Indeed, Dansgaard-Oeschger cooling events must have had a
different cause because southern meltwater input during MIS 3 does not match
their number or timing. Furthermore, the relationships between Gulf of Mexico
meltwater input, Heinrich events, Antarctic warm events, and AMOC variability
suggest bipolar warming and enhanced seasonality during meltwater episodes. We
formulate a “meltwater capacitor” hypothesis for understanding enhanced season-
ality during abrupt climate change in the North Atlantic region.

Steve Garcia
Reply to  Steve Garcia
July 29, 2015 12:11 am

Beng135 –
Ask Wally Broecker, who thought up the idea in the first place, and abandoned it when this timing evidence was shown to be solid. I would imagine he considered your scenario before giving it up entirely. The meltwater pulse was like out in the Scablands or a dam break: Everything flows straight downhill as fast as gravity drives it. No turns unless an obstacle is in the flow path. Fluids only flow downhill until they find something to splash up on – and then continue flowing DOWN.

Steve Garcia
Reply to  Steve Garcia
July 29, 2015 12:28 am

Sturgis Hooper –
Yeah, that is all known stuff, and a diversion, about meltwater heading down those available paths – almost all the time during ice advances being down the Mississippi. At 12,800, no route to the St Lawrence to the N Atlantic was available. But you are not addressing the formerly proposed glacial Lake Agassiz ice dam failure and its subsequently proposed “meltwater PULSE”. You are talking about normal meltwater, which has been thoroughly studied and understood and which has no dam break included.
They tried. They failed. It didn’t happen. NOT to the east.

July 27, 2015 4:06 pm

RISTVAN says, which is ridiculous reasoning due to the fact the YD was not an isolated event by any means and the whole period of time(20000-10000 years ago) proves that the argument WILLIS has presented about thermoregulation is wrong plain and simple. If thermoregulation was correct then the only way abrupt climatic change could have occurred in the past would have been through cosmic impacts which there are far to many abrupt climatic changes in the past to all be accounted from that source.
I was going to write an essay for the book,on this. Months of research about ‘abrupt’ tipping points in nonlinear dynamic systems. Scrapped. Willis Eschenbach is right in general about thermoregulation. YD is not a disproof

Reply to  Salvatore Del Prete
July 27, 2015 4:58 pm

SdP, I actually did research this hypothesis in depth. The motivation actually was nonlinear dynamic abrupt strange attractor shifts (a subject that I in general know more about than you might presume, having published peer reviewd on certain microeconomic consequences back in 1991). Just facts. Abandoned after the simple geophysical explanation convincingly emerged. Again just facts. Go look them up yourself–no need to believe lil’ ol me.
Focus on the abrupt end to, rather than the abrupt beginning of, YD. Therein still lies mystery.

Leo Smith
Reply to  ristvan
July 28, 2015 2:53 am

It is not inconceivable that the event was initiated by cometary impact, and ended relatively abruptly as the climate flipped attractors.
certainly a melting snow/lower albedo scenario would produce a very rapid shift just as the ice cover approached zero..
There are many conceivable explanations many of which are not against the actual evidence.
CO2 is just not one of them 😉

Reply to  ristvan
July 28, 2015 7:31 am
ristvan and any one else it was not a one time event. You are acting as if it were, the YD was not unique. Look at the data.

Reply to  ristvan
July 28, 2015 8:04 am

The mystery is the depressor(s). The climate is like a spring that bounces back whenever the heavy foot is lifted. Temperatures rebound quickly from glacial minimums but have do be dragged kicking and screaming down from interglacial maximums.

Steve Garcia
Reply to  Salvatore Del Prete
July 28, 2015 12:46 am

And not one impactor has ever hit the world since the 50,000 years of the ice cores? You DO know that up till about 210 years ago every scientists INSISTED that rocks don’t fall from the sky, right?
Read up on Bill Napier and Victor Cube’s work some time.

Reply to  Salvatore Del Prete
July 29, 2015 2:44 am

Climate is stable and Willis is right to the warm side during an interglacial.
During a cold glacial, large warming can happen until his thunderstorm regulation can even begin.
The Gulf Stream (TH Circulation) is metastable during glacials, thus the swings and switches. See:
It only stabilizes when in a warm interglacial.
That is why climate swings so widely until after the Y.D.

July 27, 2015 4:11 pm
The data in the above throw out thermoregulation as being wrong, throws out the cosmic impact as being wrong and throws out the melt water from Lake Agassiz as being wrong.
Not to mention the YD was synchronous in both hemispheres.

Steve Garcia
Reply to  Salvatore Del Prete
July 28, 2015 12:48 am

Hahaha – Just like the Little Ice Age was synchronous world-wide, in both hemispheres, too. But tell that to a warmist. Especially tell it to Michael Mann, who ill go to his grave arguing that it wasn’t.

Dan Harrison
July 27, 2015 4:16 pm

This is not a new theory, but provides supportive evidence of an impact theory that would explain a lot. A large strike has been postulated on the 1-2 mile thick ice sheet just North of the Great Lakes region. The mechanism of a comet strike is not like that of a solitary asteroid. Comets tend to break up and leave long tails as they pass around the sun. The Earth then runs into the tail resulting in many strikes, small, medium and large–most in the oceans. A comet strike would leave little to no recognizable debris, especially an airburst above a thick ice sheet. Other strikes postulated to have occurred in the same timeframe could be impacts from breakup debris (induced by passage by the sun or Jupiter, for example) of the same comet striking days, weeks or even years later as the Earth orbits annually through debris captured by the sun. One of these impacts occurred of the Southeastern coast of the Unites States in the same timeframe and was postulated to have largely wiped out a group of European migrants, the Solutrean hypothesis, a group that was the origin of the Clovis point in the Americas.
WWS mentioned the extinction of the large fauna in North America. But there is much more. In about the same timeframe what is now Yellowstone Park experienced a geological change that could easily be attributed to impact. And as far away as the region between modern India and Pakistan, an impact could have unleashed glacial dams causing massive flooding and destruction of very ancient early civilizations affected by overflow of seven (or nine) major rivers at the time.
In North America, massive flooding would have resulted from breach of a continent sized reservoir of water in Canada under the ice sheet changing the course of the St Lawrence, Ohio and other Rivers with most of North America being wiped out. (A few years ago the remains of a surviving pre-Clovis native American culture was first identified in the Northeastern New Mexico mountains–NOT Clovis.)
Multiple relatively small surviving impact craters can be seen just South of the Great Lakes region that have not been explained.
About 30 years ago I came across a Geology textbook that devoted a chapter to ancient floods in North America which had changed the course of rivers, and which had decimated much of the Northern United States. Evidence was provided in detailed reports of massive, downed buried trees over large regions in the Northern United States fitting the timeframe of this postulated comet strike. The book was already very old, almost falling apart, when I bought it at a library yard sale in Lawrenceville, Georgia, in the early 1990’s. The chapter discussed as a possible cause a comet strike as I’ve described, with the Earth passing through this comet tail after it broke up passing by the sun. The author went on to describe a referenced theory that this was a recurring comet on an approximate 5,000-year highly elliptical orbit. He went on to describe hints of older references (Greek–Egyptian) of more destructive impacts at roughly 5,000-year intervals out to beyond 20,000 years ago.
Since then I’ve noted an impact 5,000 years ago on a mountain in South America, Chili, I believe, that resulted in the deep freeze of flowering plants recently located with the thawing of a glacier at an altitude at which they could not have survived today. Then, about 5,000 years ago, there’s the unknown cause of the massive building projects such as Stonehenge (and its predecessor, Woodhenge) and the Pyramids (following revival of an ancient religion in Egypt). This all roughly fits the Mayan calendar with an approximate 5,000 year cycle of destruction and rebirth of the Earth. 10,000 years ago we are at 8,000 BC with the Sphinx and other ancient sites such as the one from which some stones for Stonehenge were reported to have been taken–not quarried.
I would really like to see all of this pulled together sometime. If nothing else, it would at least make a hell of a fictional ancient world for story telling. By the way a comet that fits this description impacted Jupiter after breaking apart into 24 separate pieces each at least a kilometer in diameter in July 1994, Comet Shoemaker-Levy 9, very close to the Mayan Calendar’s prediction. There are others …

Reply to  Dan Harrison
July 27, 2015 5:08 pm

Velikovsky put much of it together. I find it hard to believe that he hasn’t been mentioned.

Leonard Lane
Reply to  RobertLS
July 27, 2015 10:53 pm

Very odd RobertLS. Velikovsky published much and had great impact on the public and science fiction writers in the middle of the last century including books and movies. So it is odd that he is either unknown or ignored by all these impact and comet hypotheses.

Reply to  Dan Harrison
July 27, 2015 5:37 pm

Yes I noticed this recurrence too, that most if not all world megastructures are built in recurring timeframes. It looks like gravity was much weaker during building of those structures. But I doubt that it can be explained by closing of some celestial object. That would be too short time to build.

Reply to  Peter
July 27, 2015 10:38 pm

, that I guess would depend on their orbits. Velikovsky does have some interesting theories, much like Al gore. Frankly I’d believe Velikovsky long before Gore.

Rob Dawg
July 27, 2015 4:16 pm

Anything carrying enough platinum to be this prevalent would have left a hunkin’ huge hole someplace. Find the smoking hole and get back to use with something other than Bayesian models.

Reply to  Rob Dawg
July 27, 2015 4:52 pm

During the end of the last glaciation the glaciers were up to 2 miles thick, an impact on a thick glacier would not have left much behind for us to see today. I am a geophysicists and much of the seismic data I have interpreted in the glacial till areas of Canada are a mangled mess.

Steve Garcia
Reply to  LT
July 28, 2015 12:53 am

LT – OOOOOH, I’d like to pick your brain some day soon, sir.
I would say that the operative term in your gice sheet thickness is “up to”. Up to 2 miles thick. My best info is that it was 2 KM thick, maximum. Also – and I looked the very best I could – the ice thickness in the region in question was perhaps 400-600 meters thick.
If I am wrong on that, I’d love to hear more information!

Steve Garcia
Reply to  Rob Dawg
July 28, 2015 12:51 am

Yeah, it left a BIG hole in the ice sheet. Then the ice melted. Simple, right?
See the NOVA episode with Peter Schultz’s hyper-velocity experiments on ice impacts. It’s on YouTube.

Steve Garcia
Reply to  Rob Dawg
July 28, 2015 12:56 am

LT – Meet me over at sometime. PLEASE.

Reply to  Rob Dawg
July 29, 2015 2:51 am

There is a large platinum mine in Canada near the proposed impact site…

Steve Garcia
Reply to  E.M.Smith
July 30, 2015 12:26 am

E.M. Smith –
It is the Sudbury Formation, and it is a HUGE source of valuable minerals. And it is the 2nd largest impact crater on Earth.
And, YES, it is just north of Lake Huron.

Steve Garcia
Reply to  E.M.Smith
July 30, 2015 1:09 am

My bad. The Sudbury Basin.

Smart Rock
Reply to  E.M.Smith
August 1, 2015 8:47 pm

Oh come on, if you are talking about the Sudbury Basin and the nickel-copper-PGM mines there, it was formed 2.2 billion years ago, somewhat before the Younger Dryas (or even the very oldest of multitudes of dryases). But it is universally conceded that the Sudbury Basin is a meteorite impact feature).

Steve Garcia
Reply to  E.M.Smith
August 1, 2015 9:25 pm

Smart Rock –
Yeah we know that it’s 2.2B. It’s a coincidence, though, that it is VERY close to where people are kind of asking, “Okay, smart asses, where’s your crater?” Sudbury is only 50 miles or so from Lake Huron.
Actually, SOME of the evidence ORIGINALLY that put the possible YD impactor near the Great Lakes was the occasionally mentioned (here) Carolina bays. Now discarded because it didn’t work. Commenter Surgis Hooper here keeps claiming that because unworkable parts were discarded that, “The goal posts keep moving.”
But PERSONALLY, I think that any scientist worth his mettle should KEEP bad crap in his hypothesis. If for no other reason than that Sturgis Hooper doesn’t pull the “moving goal posts” attack on him . . . Everybody has to be quaking in his boots over that one. . . /snarc
Once the Carolina bays were ruled out, I am not sure the Great Lakes is the place to look, anyway. It seems that the field should have opened up.

July 27, 2015 4:40 pm

Think of it as a comet storm, rather than one major body, with meteororites impacting the earth over a period of time and over a very large area – accounts for small craters from New Mexico, to North Carolina to the Dead Sea, with lots of them having hit the ice sheet. There is a lot of widespread evidence.

July 27, 2015 4:40 pm

The real challenge to this puzzle is why did the cooling last for 1500 years?

Steve Garcia
Reply to  LT
July 28, 2015 1:02 am

YES, that is the right question to ask.
1500, and my number is 1300, but whatever, it – and other big changes in the late Pleistocene – came and went damned near the same way. The end of the YD was the last – otherwise we might not even BE here, semi-civilized and all this tech stuff at our disposal…LOL
ONE question is to ask if the 18-oxygen values in the ice cores are truly good proxies for temps. If they somehow are not, then the whole question becomes “WTF ARE they?” If they prove out, what the hell was going on there for most of 40,000 years? Hint: It doesn’t seem to show up in the climate elsewhere. Not in Antarctic ice cores, not even CLOSE to that degree.
(I actually came up with a screwball idea of how the YD could have lasted that long, but it isn’t ready for public consumption yet…LOL)

Sturgis Hooper
Reply to  LT
July 28, 2015 8:48 am

Because that is normal for D-O Events, the average duration of which is 1470 years.

Steve Garcia
Reply to  Sturgis Hooper
July 28, 2015 11:52 pm

You DO realize, don’t you? How lame that “because”? “because” is supposed to provide a CAUSATIVE action or process.
Saying that the duration is that long because it is that long is no answer at all.
Are you proud of your non-answer?
That is like explaining how a machine works by saying, “Well, I plug it in and push a button.”

Bill Illis
July 27, 2015 4:49 pm

I count 26 events in the Greenland ice cores that are more significant cooling events than the younger dryas (noting of course, there was an older dryas and a youngest dryas and a bunch of other events).
So 26 even bigger comet impacts then?

Reply to  Bill Illis
July 27, 2015 4:54 pm

Care to share your data, I have never heard of this before?

Reply to  LT
July 28, 2015 5:17 pm

“Never heard of this before”
Here is one graph of the dozens of Younger Dryases which occurred throughout the last glacial:
Bill Illis has better ones.
Just read up and learn essential palaeoclimatology and you will discover the shallow fallacy of this comet YD hypothesis.

Sturgis Hooper
Reply to  Bill Illis
July 27, 2015 7:39 pm

Correct, as usual.
There is nothing the least bit anomalous about the YD. all glacial-interglacial transitions show similar fluctuations.

Steve Garcia
Reply to  Bill Illis
July 30, 2015 2:03 am

I find it very interesting that one graph makes everybody an expert on the climate of Greenland. You counted 26 spikes? Did you do that all yourself? Are we supposed to be impressed?
And what did you count? Temperature? And in the ice cores, HOW was that temperature measured? Do you even know? Was there a thermometer in the ice core every few inches?
Are you aware that the Law Dome Antarctic ice core doesn’t show these spikes? See and look at 20,000 to present.
So, do the spikes exist all over the world? Or just in Greenland? Does anybody know? You do. You know everything. Tell me.
On the Law Dome graph there is a long upslope to the – OHMYF-INGGOD! – up to the – GASP! – the YDB! And THEN it drops off again! For, OHMYGOD! – about 1500 years!
I must be a geology and climate expert now, because I could count up to one spike!
So, dude, ya gotta tell me, since you are the expert on graph spike counting – how many is one plus none? I am not certain I counted to one correctly.
Yep, don’t forget! Those 26 spikes in Greenland – WHY aren’t they showing up in Antarctica? Uh, maybe because those spikes may or may NOT really be telling us about temperature. Or – it just occurred to my expert mind (I DID count to 1, after all, so I thin I can claim to be an expert) – maybe those spikes mean something we aren’t understanding. Nah, THAT couldn’t be true! We are all experts now!
Maybe we should check the ice cores in, say, Chicago! Oh, crap! Chicago doesn’t have any ice cores! But don’t ice cores tell the temperature all over the world? They DON’T??? DAMN, that Law Dome ice core, anyway! You guys had it all figured out, with your spike counting – and then that damned Law Dome had to come along and screw it all up…
That spike counting – that REALLY looked like a promising expert-maker. . . Maybe not…

David L. Hagen
July 27, 2015 5:02 pm
Steve Garcia
Reply to  David L. Hagen
July 28, 2015 1:05 am

Thanks for the link!

Steve Garcia
Reply to  Johanus
July 28, 2015 4:48 am

See, Michael Mann? Phil Jones? Some scientists are open about their work and post their Supplementary Information right away.

Steve Garcia
Reply to  David L. Hagen
July 29, 2015 7:00 pm
July 27, 2015 5:06 pm

There is no requirement for a large hole in the ground. We can think Tunguska (or Chalyabinsk) writ large. Maybe a Shoemaker-Levy type at extremely shallow angle of approach? And if we consider an airburst event, does it have to be an icy comet? Even a stony asteroid airburst is a possibility. It would go further to explaining the relatively small Carolina Bays impact craters without requiring an undiscovered mega crater.

Steve Garcia
Reply to  McComberBoy
July 28, 2015 1:21 am

McComberBoy – You are asking good questions – the right KIND of questions… And putting things together in pretty close to the right way to think about them.
But… Chelyabinsk convinced me that an airburst even as big as Tunguska would not have sufficient energy release to be an extinction-sized event or an event that put impact materials over a 50 million square km area. Both of those, seem to have been meteors, even though for DECADES everyone said that Tunguska couldn’t have been a meteor. A meteor OR a comet would have to be more dense and BIGGER than Tunguska in order to make it to the ground and have enough energy left over to do much more than dig a hole and a little bit. Barringer crater was about 50,000 years ago, and is 1.6 km wide (1 mile), and it didn’t do much to kill off the mammoths, even though it hit only a few hundred miles from Clovis, where the humans killed a few mammoths. So something bigger than that had to have hit. (And if it hit on the ice, add a LOT to that size, because the ice would have attenuated so much of the energy.)
YES, again a good question about comet or not. NO, it doesn’t have to be a comet. A meteor was blamed for the K-T dinosaur killer, and there is no reason a meteor wouldn’t do it. A comet, because of the higher relative velocity (up to 70 km/sec) packs more momentum energy in one way (square of the velocity), but less energy if it is less dense.
Be aware that comets as dirty snowballs doesn’t hack it anymore. Comet 67P/Churyumov–Gerasimenko, as well as comet Itokawa, turned out to have very little ice and were mostly denser stuff. Similarly Halley’s wasn’t mostly ice, either. A funny thing, too: All three of those are peanut shaped.
Carolina bays – they are not part of the YDB hypothesis. In addition, no – and I do repeat: NO – meteorites have ever been found in a Carolina bay – of which there are over 44,000 counted so far.

Jim payette
Reply to  Steve Garcia
July 29, 2015 11:52 pm

Actually, no meteorites are found in any impact craters. The largest metallic meteorite found on earth in Namibia – the size of a station wagon was just sitting on the surface. The moon meteorites found in Antarctica just sitting on top of the snow and ice. No meteorite found in that big crater in Arizona. That said, the Carolina Bays are not meteorite impact craters, most likely formed by impacting ice at less than hypersonic speed

F. Ross
July 27, 2015 5:15 pm

The researchers used Bayesian statistical analyses of 354 dates taken from 30 sites on more than four continents. By using Bayesian analysis, the researchers were able to calculate more robust age models through multiple, progressive statistical iterations that consider all related age data.

Couple of small nits. “… more than four continents…” Did they lose count after four? Why not just state the number?
And …”robust” has almost become a dirty word to use in describing the merit of a study.
Interesting study otherwise.

Steve Garcia
Reply to  F. Ross
July 28, 2015 1:24 am

Good and valid criticism of the wording. It is four. N America, S America, Europe (Belgium), and Asia (Syria).
Where is it that “robust” got a bad name” That is new to me…
Not CLIMATE SCIENCE, I hope! . . . LOL

F. Ross
Reply to  Steve Garcia
July 28, 2015 8:11 am

Hi Steve.
For several “robust” examples check out this link:
Sample quote from that post:
“… I would add one more to that top 10 list:
0. Ban the use of the word “robust” in science papers.
Of course “robust” is just another word used to reinforce the idea that a study’s author has done his job well — but, in my opinion, much overused and often abused.

Steve Garcia
Reply to  Steve Garcia
July 28, 2015 7:07 pm

F. Ross –
Yeah, I have to pretty much agree with you. There ARE times when robust IS robust, but the work should display that itself.

Steve Garcia
Reply to  F. Ross
July 29, 2015 7:04 pm

That is Anthony’s mistake, which I have suggested (below) that he correct. At this late date I don’t think he will see it.
The paper never says “…more than four continents…”
It says “…on four continents…” 3 times
It says “…across four continents…” 4 times
It says “…over four continents…” 1 time (as in “spread over four continents”)
So, to answer that question, the authors DID state the number of continents, It was Anthony who presented this wrong.
Yes, they can count to 4 – on one hand, even, if necessary.

July 27, 2015 5:30 pm

“…a cosmic impact triggered an abrupt cooling episode that earth scientists refer to as the Younger Dryas.”
Earth scientists, eh? How do extra-terrestrial scientists refer to it?

Reply to  Mark and two Cats
July 27, 2015 10:31 pm

Thanks for the laugh, I wonder now if those extra terrestrials “scientists” weren’t lobbing comets at us.
(it could have been their kids on a Friday night).

Steve Garcia
Reply to  asybot
July 28, 2015 1:30 am

Hey, if the comets were spinning, we could call it the War of the Whirls.

July 27, 2015 6:18 pm

“In a previous paper, Kennett and colleagues conclusively identified a thin layer called the Younger Dryas Boundary (YDB) that contains a rich assemblage of high-temperature spherules, melt-glass and nanodiamonds, the production of which can be explained only by cosmic impact.”
Or, and correct me if I’m wrong, by world-altering plasma electrical events, as fully scalable from laboratory bench up through to the astronomical. Some would posit thusly, it seems.
Michael S has moved on now, I believe (RIP)…a very interesting 9 minutes, with some great footage from Billy Yelverton’s lab
Hot and humid here in Ottawa, lots of thunderstorms in the region. you can “feel the electricity in the air”.

Steve Garcia
Reply to  Tiburon
July 28, 2015 1:34 am

Sorry, but electrical effects are very different from hyper-velocity impact effects.
I laid low about the electric universe idea for a few years. I had other eggs to fry. But last week I thought, well, let’s see a bit of what they’ve got. They may be saying SOMETHING useful. It was pretty sad what they are pawning off as scientific. I had to shake my head and turn the video off.
It was silly when Velikovsky came up with it, and it is silly now. I’ve got an open mind, but I also happen to know a lot of stuff that is real, and some ideas just don’t fly. . .

July 27, 2015 6:34 pm

The megafauna evolved in the CO2-rich environment of the Eocene. The herbivores required a huge amount of plant material for food. When CO2 levels declined, the super-sized slow-moving grazers could not find enough enough to eat, and the predators evolved to prey on them suffered as a result. That ecosystem was doomed by CO2 starvation.

July 27, 2015 6:35 pm

In other words, regardless of the ‘seemingly’ robust (tsk, tsk) results from the article…….and the many posts and replies from the scientifically learned, I contend that….
The science is not settled.

Steve Garcia
Reply to  kokoda
July 28, 2015 2:04 am

NO, you are completely correct. The science is NOT settled. And the YDB guys know that, too. Which is why they continue to work to find out if it holsd wateer or not. But, also, having DONE the lab tests on the materials, they HAVE found enough evidence to convince them that they are on the right track.
Really? They don’t KNOW where it is going to end up. They don’t have a crater, and they know it. They started with spikes of materials that USUALLY mean impacts. But others kibitzed and said, well, you can make nano diamonds by wiping an insect’s butt! (ignoring the REST of the suite of impact materials and pretending that because you COULD make nanodiamonds that way that it disproved anything. (They genuinely ha to know that they didn’t disporve anything.)
Are you aware, though, that ALL important points of contention by the skeptics was immediately rebutted in papers and letters to the science journals? That made the science not settled, but it made the supposed refutations a small pile of nothing.
But, to deal with the skeptics, the YDB guys kept doing study after study – on materials after materials. And every time, the results kept coming back: It is very VERY likely that this combination of materials could not have come from anything but an impact. And they FINALLY ran out of tests to run about the materials.
Let’s be clear about this: In science, ideas and kibitzers are a dime a dozen. It’s MEASURED empirical evidence that holds the high ground. And the most solid of all measured evidence is LABORATORY (forensic-type) evidence. (Does lab work count for anything in medicine? Of COURSE it does. Is it REAL science? Of COURSE it is. When you get lab tests, is THAT real, settled science? You damned well HOPE it is. When you send off a sample for Carbon-14 dating, is THAT settled science? Within the very small uncertainties of the lab tests, you bet your bippy it is.)
And that lab evidence – measuring the materials is the evidence that the YDB guys kept working on, to solidify their position. (It is all produced in the “Supplemental Information” parts of their papers, BTW – for the whole world to see and challenge.) Now, until some more sites show up with MORE impact materials to test, the YDB guys seem to be moving the whole thing forward, to the next step. They didn’t want to put the cart ahead of the horse, and they haven’t. Even THIS paper is is just an extension of the lab work – just working the results up in a better statistical way.
So, now they have done what they needed to do to nail down the TIME element (better now than before) , and they have lots more to go. They are tired of the sniping, (and poorly done) skepticisms. For them it is solid and settled enough to go to the next phase – but they know that somewhere they still might find another explanation for what they’ve found.
Show me anything in earth science from 125 years ago that is still as true as it was then. IN 125 years a LOT has transpired. Moving continents, mantle plumes (or NOT), undersea volcanoes, mid-ocean ridges and rifts, geomagnetic maps, all the climate stuff that we argue about, the ability to predict the weather days in advance and weeks in advance better than then – all sorts of things have changed. Nobody is going to expect that they will find out the truth and ALL of the truth in the first decade of a hypothesis this huge.
It took ten years for the Chixculub crater to be found, and it was found by an oil company geologists. If left to the academic geologists, even the K-T impact would be a big question mark still. It’s been all of 8 years for the YDIH. At 8 years, people were still asking Alvarez, “Where’s the crater. Luis?” Same old,same old.
And they are looking for a crater in a dead and gone ice sheet, for heavens’s sake! And they can’t even do that yet, because they first had to solidify their lab evidence. Anyone who hasn’t read a good portion of the lab evidence has no grounds to question this – has no standing..

Ian Wilson
July 27, 2015 6:56 pm

The Younger Dryas (YD) may have been started by an impact but it most certainly was not ended by an impact. Look figure 5 (of eight) at the following link:
Are the Dansgaard-Oeschger (D-O) Warm Events driven by Lunar Tides?
You will see that very rapid rise in temperatures at the end of the YD almost perfectly coincides with a Dansgaard-Oeschger (DO) event about 11,000 years BP.
I believe that the abrupt temperature changes seen in the Greenland Ice data were caused by DO event. I propose that the DO events are driven by the peak Perigean lunar tides.
It the regular DO events [roughly once every 1470 years] that are causing the temperature fluctuations that we see as the World transitioned from the Ice Age to the Holocene. It is as though the world’s mean temperature had to be jump started (by DO events) a number of times before the Holcene fired up and produced the current inter-glacial.
Here is an update of the earlier reference cited above:
DO Events Cause Rapid Warming Events in the Last Glacial Period

Steve Garcia
Reply to  Ian Wilson
July 28, 2015 2:18 am

Ian – Well and good, to assert that “It was a DO event”. Okay, now, other than steep slopes on graphs, what is a DO event?

[From your link] D-O warm events are abrupt increases in temperature to near-inter-glacial conditions that occurred during the last Ice-Age.

The temperatures increased because of “increases in temperature”???? Defining something by what its qualities are does not define a thing. You must know that.
Physically? What physical PROCESS? Name a process. It was ice-rafted debris shutting down the oceanic conveyor? No, ice rafted debris was a lot of DUST. (And not even that much, that fast.) Look it up. It’s all little grains of dirt. Them falling off of icebergs doesn’t make the temps go up 14°C and down 13°C in a matter of a decade or two. If you think it was ice-rafted debris, that is only an effect posing as a cause.
And if not THAT then what?
What MADE the icebergs come off the Labrador coast? The ice melting? Which came first the chicken or the egg? Did the icebergs coming off the coast make the temperatures warmer? So that more icebergs could come of the coast? And all of this started WHY? And it really, really ramped up fast. Why? How?
Calling it “DO events” doesn’t answer anything. Looking at line on a graph doesn’t tell us anything. WHAT do the lines represent? Only that the temps went up – according to the proxy, oxygen-18. NOTHING you see on that graph tells you WHY – only that it did. Calling it a DO event means just absolutely nothing.

July 27, 2015 7:07 pm

Date the death of the big elephants, in Siberia that died and were frozen with a full belly of good pasture.
From good pasture to frozen tundra in very short order, like overnight, would suggest that a catastrophe changed the world climate instantly. Cyclic changes to orbits or solar cycles can not do this, there are two possibilities, either we were hit by some big space rocks, or the gods were angry with us.

Reply to  wayne Job
July 27, 2015 7:30 pm

“From good pasture to frozen tundra in very short order”
Nonsense. Regardless of sudden ups and downs, there was long-term warming since the ice age maximum. How is it that the mammoths could suddenly get caught in a flash freeze that never thawed? Also, mammoth remains do not all come from the same time period. If they did we’d have no clue how long they lived in a particular area.
Consider this:

Steve P
Reply to  verdeviewer
July 27, 2015 10:19 pm

The buried, frozen mammoths were well-known to native Siberians and also the Chinese, who called them tien shu, and who also relied upon them for food, believing that they were giant subterranean rats.

Having seen how early these Siberian deposits [of fossil mammoth ivory] were known in Europe, it will not surprise us to learn that they were known also in early times in China. When Tilesius wrote his famous memoir on the Mammoth found by Adams, he was supplied by Klaproth with some curious information from Chinese sources. He says, when he was at Kiachtu on the Chinese frontier in 1806, he learnt from several Chinese that Mammoths’ bones were known to them, and were called Tien shu ya, Teeth of the Mouse, Tien shu. On turning to a Manchu dictionary, he found the statement that the beast Fyn shu is only found in a cold region on the river Tutungian, and as far north as the frozen ocean. “The beast is like a mouse, but the size of an elephant. It shuns the light and lives in dark holes in the earth. Its bones are white like elephant ivory, are easily worked and have no fissures, and its flesh is of a cold nature and very wholesome.”
The great natural history written in the sixteenth century, and entitled Bun zoo gan rom, says—”The beast Tien shu is mentioned in the ancient ceremonial written in the fourth century B.C., and is called Fyn shu and In shu, i.e. ‘the self-concealing mouse.’ It is found in holes in the ground, has the appearance of a mouse, but is as large as a buffalo.

Steve Garcia
Reply to  verdeviewer
July 28, 2015 2:29 am

Verdeviewer – “…mammoth remains do not all come from the same time period.” Of course not, they died where they lived, at the end of the time when each individual died. But look up on a map where the Siberian mammoth bones and carcasses are found. 95% of that area is now the coldest region on Earth except for Antarctica. The mammoths nor their food could survive in that region – not now they can’t. And if they can’t now, then they couldn’t then. Those flora in their digestive tracts tells it all. The place that the bones are found are not the places NOW where mammoths lived.
How to explain that? Did the dead bodies with the food inside move? Not in any way we can imagine. Did the dead bodies get up and ALL walk north to the Arctic Ocean peninsulas? Sounds like a not so scary movie these days.

Reply to  verdeviewer
July 28, 2015 7:16 am

verde please explain how these animals moved a thousand miles north to die with a stomach full of good pasture, they must have caught a very fast train.

Reply to  verdeviewer
July 28, 2015 8:09 am

“please explain how these animals moved a thousand miles north to die”
They didn’t.

Reply to  wayne Job
July 28, 2015 7:35 am

Steve Garcia opines that neither “the mammoths nor their food could survive in that region.”
“Fifty-thousand years ago, the present-day arctic tundra was a vast grassland through which mammoths, woolly rhinos, reindeer and even lions roamed.”
“The habitat of the woolly mammoth … stretched across northern Asia, many parts of Europe, and the northern part of North America during the last ice age. It was similar to the grassy steppes of modern Russia, but the flora was more diverse, abundant, and grew faster… This habitat was not dominated by ice and snow, as is popularly believed… “
The woolly mammoths along the south edge of the Laurentide ice sheet were extirpated before those in eastern Siberia, and there’s evidence humans played a part. Further south, the Columbian mammoth went extinct around the same time.

Steve Garcia
Reply to  verdeviewer
July 28, 2015 1:12 pm

verde – The NPR article got off on the wrong foot ehen they wrote:
“They were some of the largest, hairiest animals ever to walk the Earth, but new research shows a big part of the woolly mammoth’s diet was made up of tiny flowers.”
Hahaha – this isn’t new research. This has been known since the first mammoths were found a bit, because flowers were found in their mouths and guts. They didn’t mention the other stuff in the guts. Flowers makes a much better story. Ah, yes, the buttercups! Even though this article said the flowers were LIKE buttercup, buttercups is specifically what earlier reports asserted.
Buttercups [from Wiki] :
“All Ranunculus species [buttercups] are poisonous when eaten fresh by cattle, horses, and other livestock, but their acrid taste and the blistering of the mouth caused by their poison means they are usually left uneaten. Poisoning can occur where buttercups are abundant in overgrazed fields where little other edible plant growth is left, and the animals eat them out of desperation. Symptoms include bloody diarrhea, excessive salivation, colic, and severe blistering of the mouth, mucous membranes and gastrointestinal tract. When Ranunculus plants are handled, naturally occurring ranunculin is broken down to form protoanemonin, which is known to cause contact dermatitis in humans and care should therefore be exercised in extensive handling of the plants.”
There are 64 varieties of buttercups. One that is possible in the Siberia is this:
“Ranunculus lapponicus (the Lapland buttercup) is distributed all over the arctic, with the exception of northern and eastern Greenland.
It is a low, prostrate plant with a creeping, underground stem (rhizome) which sends out long stalks and shoots bearing the flowers. The leaves are deeply tripartite, forming 3 lobes which are toothed or crenated. The flowers are yellow, solitary, generally having 6 (8) petals that are distinctly longer than the sepals. After flowering, the fruit forms a globular head of carpels held above the creeping plant.
It grows in wet localities, especially in moss carpets along beaches, streams and lakes.
So, rather than this idyllic visions of large, dancing pachyderms munching sweetly on some pretty flowers, we have a poisonous plant that is only eaten out of desperation. They didn’t happen to mention that in the article, did they? I wonder if the diarrhea was found under or on the carcasses and bones? No, there is mention of diarrhea? Only mammoth poop”? Strange. What are they not telling you?
Buttercups bloom in the spring. What do the mammoths eat the rest of the year? When the temps dive to -60°F and -80°F? You know, the 9 months of the year when northern Siberia is FROZEN? Do they do like bears and hibernate? Of course not.
Elephants need 200-600 pounds of food a day. Tiny flowers, indeed. Yes, they ate the PLANTS that were flowering – which is what the article actually says.
The article continues:
“And when the flowers disappeared after the last ice age, so too did the mammoths that ate them.”
Geez… The last ice age was the Wisconsinan in N America and the Weichselian in Eurasia. That last one was FAR from the worst of the ice ages in the Pleistocene. It was not even as bad as the Last Glacial Maximum, which ended about 22,000 years ago. Miraculously, the mammoths survived those earlier, more severe, ice ages. So why would they all die off from the littlest of the true ice ages? The article doesn’t even attempt to explain why the weakest of the ice ages should be the one that killed off the mammoths.
FUNNY, isn’t it? How the mammoths dies out “when the flowers disappeared”, but not when the flowers died for 9 months every year. Those must have been some SKINNY mammoths.
It IS true that the ice sheets did not extend into Siberia east of the Urals. It was too cold for snow. The Arctic Ocean coast was ice-free, but it was not a tundra. The nearest latitude for the flowers in the mammoths’ mouths and guts was FAR to the south.
Look up “Tundra” and specifically “Arctic tundra”. Then ask yourself if these mammoths could survive there on the food that is only available about 2-3 months out of the year.

Reply to  verdeviewer
July 28, 2015 6:02 pm

The flowering plants were forbs, and forbs may have died out from lack of megafauna poop.
Flowers, however, weren’t the point. Whatever they were chomping, they clearly weren’t starving.
Oh, and BTW, here’s the “barren tundra” near where the “Adams Mammoth” remains were found:comment image
“Lena River near Yakutsk (synchroswimr)” by “synchroswimr”/Stacy, Minneapolis – Licensed under CC BY 2.0 via Wikimedia Commons –comment image

Reply to  verdeviewer
July 29, 2015 2:13 pm

More on mammoths, buttercups, and forbs…
There’s a reference to mammoths eating buttercups in “Paleoecology of Beringia”. Analysis of food in the Beresovka mammoth’s gut and mouth identified 5 grasses, 2 sedges, mint, poppies, oxytropis pods and beans, and buttercup seeds.
Oxytropis is a forb. Oxytropis didn’t “disappear”–it still grows where mammoth remains are found.
“Seeds” indicate the mammoth died in the autumn, when buttercups would not have been poisonous. But some oxytropis subspecies are known as “locoweed.” Eating too much locoweed could have resulted in herds of mammoths and rhinos staggering about, tumbling down riverbanks or falling into mudholes. Not a pretty picture.

Reply to  verdeviewer
July 29, 2015 9:21 pm

Holy samoly, I just perused the research paper that prompted the NPR article.
There are 13 forb families listed as megafauna foods, and none of them are oxytropis.
Poppies, however, are on the list. And that raises serious questions:
Did megafauna die out from drug addiction?
Are NPR reporters equally vulnerable?

Steve Garcia
Reply to  verdeviewer
July 29, 2015 9:42 pm

@verdeviewer July 29, 2015 at 2:13 pm –
Hmmmm, there is apparently a good bit of contradictory reportage out there. Some say buttercup flowers, and those point to it as evidence of death in springtime. And you now present buttercup seeds, which indicate autumn. Some clearly state that grasses were NOT eaten by the mammoths, and this one of yours presents “5 grasses”.
Contradictory stuff.
Note to Steve’s brain: Don’t even TENTATIVELY conclude anything for a while… Just keep on accumulating information….

Steve Garcia
Reply to  verdeviewer
July 30, 2015 1:38 am

@verdeviewer July 28, 2015 at 6:02 pm –
Good photo of present day Lena River during the 3-month summer – which is like spring anywhere else. What was it like the rest of the year – and back in the ice age?
The photo says “near Yakutsk”. The Yakutsk I know of is THIS one: “Yakutsk: Journey to the coldest city on earth”
8 Months of the year the average daily temp is below freezing. What do the mammoths eat the other 9 months? 5 months of the year the weather is “frigid” meaning BELOW -9°C (15°F) close to 24 hours a day. If nothing else, that means nothing grows. And for 2 more months the weather is “freezing” – from 0° to -9°C. Again, meaning that nothing grows.
These are the most voracious eaters on dry land, needing 200 to 600 pounds of food a day.

Reply to  verdeviewer
July 30, 2015 10:50 am

C’mon, Steve G., you won’t find the answer to your question on tourist sites.
How do the local reindeer, long-horned goats, ibex, and musk deer survive Yakutsk winters?
What do elephants do when seasonal changes dry up their food and water supply?
This mammoth seems to be a relative outlier based on tummy contents:
Others apparently chomped twigs and bark of alder, birch, larch, and spruce during the winter, much like reindeer (some species of which migrate 1000s of miles per year).
You noted that a lot of current arctic plants are small and poisonous. Could it possibly be that the plants evolved as a result of overgrazing? Could it not have been an evolutionary battle that required mammoths to become smaller and poison-resistant and the mammoths lost?

Ian Wilson
July 27, 2015 7:17 pm

The following paper concludes that:
Wilson, I.R.G. Are the Strongest Lunar Perigean Spring Tides Commensurate with the Transit Cycle of Venus?, Pattern Recogn. Phys., 2, 75-93
If the mean drift of the 31/62 Perigean spring tidal cycle is corrected for the expected long-term drift between the Gregorian calendar and the tropical year, then the long-term residual drift between: a) the 243 year drift-cycle of the pentagonal pattern for the inferior conjunctions of Venus and the Earth with respect to the nodes of Venus’s orbit and b) the 243 year drift-cycle of the strongest seasonal peak tides on the Earth (i.e. the 31/62 Perigean spring tidal cycle) with respect to the tropical year is approximately equal to -7 ± 11 hours, over the 3000 year period [from 1 to 3000 A.D.].
The paper makes the following very speculative extrapoolation from these conclusions:
Finally, there is one speculative extrapolation that could encourage others to further investigate this
close synchronization on much longer time scales. If these future investigations show that the long-term residual drift rate of -7 hours over 3000 years is valid over much longer time scales, then this close synchronization may highlight a mechanism that might be responsible for the Earth’s 100,000 year
Ice-Age cycle. This comes from the fact that the strongest Perigean spring tides would be in close synchronization with (i.e. ± half a day either side of) the date of the Earth’s Solstice (on or about December 21st) for a period (24/7) × 3000 years =10,300 years. In addition, this close synchronization would
be re-established itself after the 31/62 peak tidal pattern drifted backward through the Tropical calendar by ~ 9.7 days (i.e. the average vertical spacing between sequences in figs 12 a & b) such that after ((9.7 x 24) /7) x 3000 years = 99,800 years. Hence, the close synchronization discovered in this study lasts
for ~10,000 years, with each period of close synchronization being separated from its predecessor by ~100,000 years. This is very reminiscent of the inter-glacial/glacial period that is characteristic of the Earth’s recent Ice-Age cycles.

Richard M
July 27, 2015 7:41 pm

I’m not sure why the two theories have to be mutually exclusive. An impact could have been what opened the way to let Lake Agassiz release its water.

Reply to  Richard M
July 27, 2015 7:56 pm

“I’m not sure why the two theories have to be mutually exclusive.”
Me neither.
And it seems highly unlikely the hypothesized impact could have had much influence on the 8.2 ka event.

Steve Garcia
Reply to  Richard M
July 28, 2015 2:33 am

Good point…

Steve Garcia
Reply to  Richard M
July 28, 2015 2:34 am

Except it takes the cause and makes it the effect, and vice versa. That is a big difference.

Steve Garcia
Reply to  Steve Garcia
July 28, 2015 2:35 am

My brain is tired. I meant the meltwater becomes the effect not the cause. Forget the vice versa part…

richard verney
July 27, 2015 7:49 pm

Why at this late stage in the history/evolution of the solar system would there be such a bombardment?
I would want to see evidence of recent impact bombardment on the moon and Mars before I would consider this to be anything more than speculation.

richard verney
Reply to  richard verney
July 27, 2015 7:59 pm

At 5 am, I misread the article. Obviously, I can accept a one off impact as a possible explanation.

Steve Garcia
Reply to  richard verney
July 28, 2015 2:41 am

Look up astronomer William Napier, about the Comet Encke and its progenitor (father). The Taurids are a stream of rocks of varying sizes that the Earth passes through twice a year. Napier has worked out that the progenitor of Encke broke up about 30,000 years ago, and that we’ve been at risk of the fragments ever since. He is not alone in thinking this. He asserts that in the early centuries after the break-up the fragments were much more plentiful than now – and that their numbers decreased over time (meaning they HIT some planet), so that now we don’t get much because they are thinned out. But he says that the stream is not evenly spaced out along its orbit. It, in fact, split into a north and south stream at some point. And we sometimes get one and sometimes the other. No one knows how many Taurids three are, and no one knows how big the other fragments are. Encke itself is like three miles across. NOT one we want hitting us – but it is out there.

Don Easterbrook
July 27, 2015 8:28 pm

This is an old story with the same old bad logic. I’ve written several articles and responses to this nonsense but it just keeps popping up–comets seem to be blamed for a many not-well-understood phenomena. Here is what I wrote about the same story in 2012.
March 12, 2012 at 8:20 am
Before jumping on this bandwagon, consider the following:
1. There may well have been a meteorite impact near the beginning of the Younger Dryas (YD), but that doesn’t prove it was the CAUSE of the YDs. It’s the same logic as saying the cause of the 1978-1998 warming coincided with rise in CO2 so the cause must be CO2. Bad logic.
2. The YD is just the most prominent of many Dansgard-Oerscher abrupt climatic events.
3. The YD ended just as abruptly as it began a little over 1000 years later.
4. The YD corresponds with changes in 10Be and 14C production rates, suggesting changes in incoming radiation and pointing toward a Svensmark type cause.
5. The problem with single event causes (e.g., volcanic eruption) is that they cannot be sustained for the length of time of the climate change. If the idea is that the cooling was caused by ejection of dust into the atmosphere, that wouldn’t last for more than 1000 years.
6. If the YD was caused by dust in the atmosphere, it should show up in the Greenland ice cores (where even very small, annual accumulations of dust from summer ablation are well preserved). There is no such evidence of dust from an impact event throughout any of the well preserved YD ice core record.
7. The list goes on and on–too many to include them all here. Perhaps a longer response later. The bottom line is that a single event, meteorite impact event doesn’t prove the origin of the YD.
Before jumping on the comet bandwagon, a number of dots need to be connected and some critical questions need to be addressed. For example, how could a single event, even with multiple projectiles, cause an ice age that lasted for more than 1,000 years? Surely not from atmospheric dust and if not that, then what? The Younger Dryas is not the only climatic event during the post glacial maximum period—there are also a number of others spanning the time from 14,500 radiocarbon years (about 17,500 calendar years) to 10,000 14C years (about 11,500 calendar years). These are well known, well dated, and well documented in ice cores and in the global glacial record. So the question is, how could an impact event cause both multiple warming and cooling events over a 3,000 year period? Doesn’t seem logical at all for either impact or volcanic events.
Some other questions pertain to the evidence for the proposed cosmic event. Geologists are used to studying micro-images of rocks and looking at the two samples shown in the paper, it is obvious that both show definite flow structures that closely resemble glass flows from volcanic lava. The statement “Morphological and geochemical evidence of the melt-glass confirms that the material is not cosmic, volcanic, or of human-made origin. “The very high temperature melt-glass appears identical to that produced in known cosmic impact events such as Meteor Crater in Arizona, and the Australasian tektite field,” is very vague. What morphological and geochemical evidence? As for these specimens being identical to trinitite from atomic blasts, there is surely no flow structure in the photos shown so how can they be identical?
The bottom line here is—a lot more dots need to be connected and these critical questions (as well as a number of others) need to be addressed before concluding that the Younger Dryas was caused by a cosmic impact.
For background on what the Younger Dryas is and isn’t, see:

Steve Garcia
Reply to  Don Easterbrook
July 28, 2015 2:48 am

“6. If the YD was caused by dust in the atmosphere, it should show up in the Greenland ice cores (where even very small, annual accumulations of dust from summer ablation are well preserved). There is no such evidence of dust from an impact event throughout any of the well preserved YD ice core record.”
Actually you are wrong on this, to some extent. Not in an ice core. The YD scientists found a layer that dates to the YDB in the Greenland ice sheet, with nanodiamonds.

Don Easterbrook
Reply to  Steve Garcia
July 28, 2015 7:38 am

No, I’m not wrong–you’re missing the point here. If a comet impact put enough dust in the atmosphere for more than 1,000 years to cool the climate, that’s a lot of dust–where is all this dust in the ice core? How can this explain the many other abrupt periods of cooling at the end of the Pleistocene and the abrupt end of the YD?

Steve Garcia
Reply to  Steve Garcia
July 28, 2015 1:19 pm

Don – No, I am not missing the point. But you ignored my information.
I have the same questions you have. But I don’t jump to conclusions. These people haven’t had time to develop their entire hypothesis nor its ramifications or deal with its weak points. They haven’t had time. They’ve been doing the foundational work, lab work, to first prove one way or another that what they have is impact materials. That they have come to the end of, otherwise they wouldn’t be collating it in this Bayesian paper. Give them time. Rome wasn’t built in a day.
Do you even REMOTELY think that they haven’t thought of those questions, too? Before any of us? Do you take them for fools?
If they went off replying to everyone who had a point of contention about peripheral issues, they would be poorly organized and poorly disciplined scientists. Which they are not. One thing at a time.
You’ve asked and not gotten any answers. It all has to be done on your time schedule? Hardly.

Reply to  Don Easterbrook
July 28, 2015 8:07 am

Don, you are 100% correct.

Sturgis Hooper
Reply to  Don Easterbrook
July 28, 2015 8:40 am

All true, but there is much more. It has been hashed and rehashed here because our esteemed host keeps drawing attention to Kennett’s baseless, repeatedly falsified drivel.
The YD Impact fantasy has even less support than catastrophic man-made global warming hypothesis. Both fail to reject the null hypothesis, ie that the YD is no different from the thousands of other such sudden warming and cooling events during the Pleistocene.

Steve Garcia
Reply to  Sturgis Hooper
July 28, 2015 1:20 pm

Ah, Mister Sturgis Hooper, the man who decided before he ever read anything academic that this was wrong. What’s new?

Sturgis Hooper
Reply to  Sturgis Hooper
July 28, 2015 1:38 pm

I’ve read far more things “academic” than you have, obviously.
I’ve known this was pure bunkum from the very first paper spewing this nonsense, as has the geological community. It’s a bad joke.

July 27, 2015 8:32 pm

This is a convenient way of ruling out or avoiding greater research into a cosmic ray event. A possible increase in cosmic rays from a super nova within 100 light years of earth could last several decades. The Be-10 in the ice cores of Greenland and Antarctica do show an increase around that time when layer thickness is also taken into account. But lets ignore cosmic rays, they can’t be taxed.

Steve Garcia
Reply to  NucEngineer
July 28, 2015 2:51 am

Dude, This all started out with Richard Firestone. Cosmic rays are right up his alley. He thought originally that is what it all was. So, you are completely claiming things off the top of your head, and you don’t know anything about the history of this hypothesis.

Steve Garcia
Reply to  Steve Garcia
July 28, 2015 3:09 am

Sorry that that all was bold. Only one sentence was intended “Cosmic rays are right up his alley”

John F. Hultquist
July 27, 2015 9:08 pm

Seems there is no consensus that Lake Agassiz drained abruptly nor entirely into the North Atlantic:

Steve Garcia
Reply to  John F. Hultquist
July 28, 2015 2:55 am

Well, good, it is good that the UM is not giving the students out-of-date ideas. Even Wally Broecker who came up with the idea abandoned the idea when he faced the evidence that the outlet was simply not available at the YDB. Theere shouldn’t be ANY consensus AT ALL that this is what happened, because it is flat WRONG.
In fact, in response to the convincing evidence against it, some die hards thought to have the meltwater pulse go NORTH out the mouth of the MacKenzie River – about as far from the Atlantic as you can go in Canada.
It’s an accepted reality: The glacial Lake Agassiz did NOT drain abruptly out into the North Atlantic.

July 27, 2015 9:17 pm

Veli *cough* ski

Michael Jaye
July 27, 2015 9:25 pm

The essence of the problem has to do with geologists: for nearly 200 years they have accepted that the Earth has had all of its water since nearly its beginning. This belief follows from observations and debates in the early decades of the 1800s when geologists discerned that diluvial gravels belonged to multiple, distinct events; thus, they concluded that there was not a single worldwide flood.
During that period, The Geological Society of London’s president, the Rev. Adam Sedgwick, publicly recanted his belief in a worldwide flood. He said: “…the vast masses of diluvial gravel … do not belong to one violent and transitory period. It was indeed a most unwarranted conclusion when we assumed the contemporaneity of all the superficial gravel on the earth…. Having been myself a believer [in a worldwide flood], and, to the best of my power, a propagator of what I now regard as a philosophic heresy … I think it right thus publicly to read my recantation.”
Some geologists have argued that Sedgwick’s proclamation initiated the “no flood, ever” paradigm.
But the conclusion is incorrect. Instead, it should have been: presently exposed landscapes were not inundated by a presumed worldwide flood. This is the only conclusion that could have been drawn from the evidence, and it is wholly different from claiming that there was not a worldwide flood.
We should let that sink in: two-hundred years of geology and related fields have been affected by this fundamental error.
What brings it to our attention? Fire up Google Earth or maps (satellite view), and investigate the submerged features off Monterey, CA, or San Francisco, or the Gulf of Alaska, or the Celtic Sea, or the Mediterranean Sea, etc. All around the planet we can identify well preserved topographic features that are evidently submerged rivers and drainage systems. How could they be in such depths if there was never a worldwide flood?
One explanation holds that these features were carved by turbidity currents. For instance, one article from the literature is “Submarine canyons in the bathtub” that claims these sediment flows are rarely observed mainly for two reasons: the “difficulty in making measurements and observations on active or abandoned channels, and the probably long time scale, on the order of thousands of years, needed to develop these structures, that forbids the observation of processes on a human time scale.” As most of us know, it is impossible for focused currents in the deep ocean to persist over the distances involved (it is 200 km from the beginning of Monterey Canyon in Moss Landing, CA, to the system terminus to the southwest), so why do geologists believe such fantasy?
There are two reasons: (1) when investigations into the structures began, the full extent of the systems was unknown – they were assumed to be found only along continental shelves where gravitational gradients might support turbidity currents; (2) geologists’ early 1800s conclusion that the Earth has had its present amount of water since nearly its beginning. A consequence of (1) is that a body of published works was built upon it, and a consequence of (2) is that it has prevented the problem’s resolution. Geologists have conflated cause and effect, and they are fitting observations (submerged features) into theory (no global flood).
Now consider that there was a worldwide flood….
Then those topographic features would have been subaerially carved and then submerged quickly by a nearly unimaginable amount of water. Such a volume cannot be stored at the poles so it must have a cosmic origin. Then the object must have been much larger than a comet but similarly composed – fragile, porous, predominantly water ice, but with other minerals, too. Its high velocity impact would cause some damage to the planet, but it wouldn’t be fiery or catastrophic because of its porous nature. Impact interactions by the minerals would create the YD nanodiamonds, and its waters would flood the former abyss. Surviving humans would record the event in their oral traditions. The addition of such a volume would irrevocably change the Earth ecosystem, and humans would be ill-adapted for the post-flood Earth they now encounter.
Without giving away the impact site, it’d be interesting to learn whether WUWT readers could identify it using Google Earth or maps. Hint: it’s huge but subtle, it’s in the Southern Hemisphere, and it’s now submerged.
There was a worldwide flood. It was delivered by a cosmic impact about 13kybp, it created the YD nanodiamonds and associated ecosystem changes, it submerged the myriad drainage systems found in continental margins around the planet, and it is commemorated in ubiquitous human oral traditions.

Reply to  Michael Jaye
July 28, 2015 1:09 am

*** HINT *** it’s location is related to a region of the Earth’s crust that is defined by a complex tectonic arrangement which appears to be circular and is close to a hotspot.

Reply to  Michael Jaye
July 28, 2015 6:32 am

Biggest load of hogwash I ever saw. –AGF

July 27, 2015 10:34 pm

My hypothesis is that it was caused by Stone Age Mankind having an use of stones that was no longer sustainable and addition created a cloud of stone dust that covered the whole Earth?

Reply to  Santa Baby
July 28, 2015 1:49 am

Yeah, cavemen probably suffered from peak-stone, too…

July 27, 2015 10:56 pm

Maybe. But why not a slight increase in the density of the Local Fluff? (Local Interstellar Cloud)

July 27, 2015 11:29 pm

Reading this paper and the comments on this thread show in vivid relief the complete loss of integrity the field of climatology has brought upon itself.
Because of climatology’s rampant and unethical raw-data “adjustments”, continued reliance on utterly unskilled climate models, $billions of agenda-driven CAGW research grants, the politicization of the CAGW hypothesis, the antagonistic attitude towards genuine skeptics, the complete absence of constructive debate, etc. have all created an atmosphere where any new climate paper is met with contempt and cynicism rather than healthy skepticism; and rightfully so.
Because the CAGW hypothesis spills over into so many different fields of study: epidemiology, oceanography, geology, astronomy, physics, chemistry, mathematics, statistics, biology, physiology, medicine, philosophy, economics, politics, etc., all these fields are being tainted and slowly destroyed from within by a stubborn adherence to a failed hypothesis.
When “science” loses its integrity, it becomes worthless, leading to: wasted money, lost lives, bankrupt companies, poverty, wars, lowered standards of living, economic stagnation, higher unemployment, larger deficits, inefficiencies, apathy, frustration, anger and lack of human progress.
Man is the only animal whose survival is entirely dependent upon its ability to objectively use reason and logic. When logic and reason are replaced by pragmatic subjectivism, man loses his humanity…
The disconfirmation of the CAGW hypothesis can’t happen soon enough….

Steve Garcia
July 28, 2015 3:14 am

It might be useful for everyone to see just what is out there. This terrific video shows how many asteroids have been known, over time, and how that population has gone up a LOT with the WISE mission.
Earth crossers are in RED.

Ivor Ward
July 28, 2015 4:03 am

The superstitious ancients viewed comets as a presage of coming disaster. It would appear that we have learned nothing in the last 40,000 years and still live by superstition.

Steve Garcia
Reply to  Ivor Ward
July 28, 2015 4:39 am

I said it to someone else: Have you ever read anything by astronomer Bill Napier? He and others like him present the case that the ancients had good reason to be sacred of comets and other things in the night sky – that Earth’s orbit was much more populated by objects at times in the last 30,000 years, and that many of them hit the earth in the time of man. Such a history, if real, would explain why they gave names to the objects and had reason to fear them. It might also explain why so many communities had large megalithic astronomical stone circles. We will be a long time understanding what the full purposes of the stone circles were. Yes, we’ve identified the sunsets and solstice sunrises and such – but it doesn’t explain why they would put so much effort in the OTHER stones. I don’t know the answers myself. Also why did they so often build so massively, in so many places around the world?
The Mayan’s Chilaam Balam at one point describes how the Milky Way (the alligator in the sky) rose up. Did they mean it figuratively? Arkies say so. WHY do over 500 ancient cultures have a destruction myth with so many features in common, almost always with a devastating flood and burning things falling out of the sky? Many of them of such objects, destroying and killing and burning, and roaring and buzzing – with “beards”, as the arkies translate it. One man’s beard on a comet is another man’s tail.
To the arkies, these are all just mumbo-jumbo tales. Did you ever wonder WHY any king would consult seriously with an “astrologer”? How DUMB can people of the past have BEEN, after all? Astronomy, whether they admit it or not anymore, grew out of astrology. But which was which, in the long distant past?
WHY would anyone consider those little points of light that hardly move from day to today (the planets) to be gods? We look up and yawn. They made them into gods and assigned them abodes and powers. WTF?? wwe all think now, right?
But is it totally impossible that we are missing something in our own past? Except for moments like Chelyabinsk in 2013, the night sky and day skies are quiescent places. And because they are in our time, we assume that they were always that way.
We now know of more than half a million asteroids, with ones the size of Tunguska that cross Earth’s orbit numbering over 1400. How much shift would it take for a few dozen of those to endanger us? Obviously, with all the craters out there on planets and moons, the solar system had a lot of things going boom in the night at one time and for a long time. We are told that that was all millions and billions of years ago. I am sure some of it was. But I’ve read enough astronomy pepers to understand how much bluff is in most of them. Assumptions piled on assumptions. And then those who know all about it all, we find out that when we send probes to Vesta and Ceres, we find out that Vesta isn’t what we thought it was – AND that some astronomers are reading the new evidence to re-think the entire history of the solar system. How much do we rally know about the solar sytem? More of it than we know is assumptions and guesses. Asssumptions with good reason, and good guesses. But they really missed on Vesta. How many other things are they guessing wrong about? Are they really s wise as we give them credit for?
This isn’t any of us being climate warming alarmists. This isn’t us being Creationists. These are scientists, doing LAB work, for Pet’s sake. They aren’t imagining the characteristics of the materials they re finding. They are REAL materials, with REAL characteristics that are normally ALWAYS interpreted as impact materials. But another group (doing sloppy replication work that was called out and showved in their faces in rebuttals) waves their arms around and asserts that the lab work is wrong. (Never once proven), and thus theis is all a bigger hubbub than it should be. These scientist are NOT going around saying we are going to get hit some day. Other people might be saying that, but this group of scientists is not. All they are saying is that there is FORENSIC-style, measured evidence that seems to say that Earth was hit a long time ago.
When someone says that tektites are impact related, do you accuse them of being warmists? When someone finds a meteorite, do you accuse them of being an alarmist? When Chelyabinsk happened, did you accuse the people there of being alarmists? But I assure you, almost everyone there was very happy that that meteor was only 17 metres and not 170. We might or might not have seen a 170 meter one coming. NO time for doing any alarm thing there, is there?
Did you run around accusing Luis Alvarez of claiming that we are going to get hit by a dinosaur killer? Ah, maybe you were. But Alvarez wasn’t saying any such thing. Neither are these scientists. If you read that into THEIR work because of what some people HERE are saying, you aren’t paying attention.
As to “superstitious ancients”, with our world divided by religious peoples at home and abroad, pointing to the ancients as if we don’t have our share, that makes little sense. I grew up near one of the hearts of evangelism; I can assure you superstition is far from dead in this modern world.

Reply to  Steve Garcia
July 28, 2015 7:34 am
How do you explain all of the other abrupt climatic changes ? I doubt they were all caused by extra terrestrial impacts.

Reply to  Steve Garcia
July 28, 2015 10:52 am

Astrology, the belief that stars control our destiny, is a relic of the belief that planets were gods and stars were demigods or angels. It’s a curious quirk of history that this superstition survived any form of monotheism, let alone Christianity and the Enlightenment. –AGF

Reply to  Steve Garcia
July 28, 2015 11:48 am

This is as anthropologically naive as it gets–pagan creationism–Velikovsky copycats. When are these cosmic catastrophes supposed to have occurred, 10ky? And their oral histories survived, independently, all over the world? If it were possible for legends to persist so marvelously, we could not call them independent since they could have been carried across the Bering Strait or anywhere else–could even have a single source which dispersed everywhere, like the Baltic Sea flood theory.
Skies full of comets, 10ky? There ought to be some terrestrial or lunar evidence. Astrology buffs still believe the stars control human destinies. This belief is a relic of animism–everything is alive–trees, springs, rocks; especially things that move, like stars. And the planets move through the stars–they’re the bosses, the gods. Stars are demigods or angels. Monotheism didn’t make a dent in this world view, or Christianity: Christ was “the bright morning star” (the Pseudepigrapha frequently identify stars with angels). The Copernican revolution eventually did make a dent when stars were deduced to be inanimate suns, and Church and all obliviously accepted this doctrine without worrying at all whether the rug had been pulled out from under astrological superstition. Copernicus unintentionally relegated astrology to the realm of paganism, and nobody made a fuss. The astrologers remain in communion.
The meteor shower of 1833 was unprecedented, and heralded the end of the world for millions. But it led to the scientific investigation of meteors and modern theories of their origin with comets. I’ve heard of the 100my comet cycle, but nothing to explain a modern myth of numerous comets any time in recent geological history. This is a rather imaginative theory, but it explains your adherence to the ET origins of the YD–there ain’t nothing rational about it. –AGF

Steve Garcia
Reply to  Steve Garcia
July 28, 2015 12:35 pm

Not avoiding your question, but it is SERIOUSLY premature to think that a couple of O18 graphs is the full story of the climate back then. Note that the Antarctic ice cores don’t show nearly as much change. THAT suggests two things (maybe more) – that the Greenland ice cores are showing extremes, and that O18 may not be the proxy that we think it is. After all, we here are finding out that tree rings are all over the place and must be read with care – not counting the Divergence Problem.
In addition, Greenland was directly east and downwind of the center of N American ice cap, which was situated in Labrador east of Hudson Bay (the thickest ice). What does that do to the temps, with katabatic winds blowing all around Greenland, even if not directly over the high ice. STRANGE weather exists in such places, to begin with. And certainly the center of a high ice sheet is not presently indicative of the weather patterns of the rest of the world. So, be careful with what you read into the ice cores. The apparent ups and downs – why does everyone accept those at face value? We have people worrying over 2°C possibilities, but there the O18 suggest 13-14°C and nobody bats an eye. They accept it as rock solid. I don’t understand how they can. Merely having shifting wind patterns could make the temps go up and down like that – and would be a much better explanation than the current one, which is “Well, it warmed up and cooled down”. That is not an explanation of cause, only of effect.
It’s like th guy above who claimed that the cause of the warmups and cool downs was the DO events. NO. DO events are in themselves simply the artifacts of the ice core graphs, literally described as “sudden large temperature changes.” Well, you can’t explain sudden large temperature changes by DO events when DO events themselves e “sudden temperature changes.” You can’t explain something by itself and giving it a name.

Steve Garcia
Reply to  Steve Garcia
July 29, 2015 2:23 am

agfosterjr – Astrology and the stars. Firstly, you didn’t read Napier. Secondly, astrology is not about stars “controlling our destiny” but about planets. If you are going to diss something, you should at least get your facts straight.

July 28, 2015 6:28 am

Four days ago it’s abrupt warming:
Today it’s cooling (?) caused by a comet. Or dogs. Or pathogens. All of which specialize in big game extinctions.
Well we know that humans liked to hunt big game–one kill feeds the clan–a whole lot easier than killing a few hundred rabbits. And we know that climate has been oscillating for millions of years. And that everywhere humans go they wipe out the big game fast, rain or shine. But the debate rages on. –AGF

Reply to  agfosterjr
July 28, 2015 7:31 am


Well we know that humans liked to hunt big game–one kill feeds the clan–a whole lot easier than killing a few hundred rabbits. And we know that climate has been oscillating for millions of years. And that everywhere humans go they wipe out the big game fast, rain or shine. But the debate rages on. –AGF

We know absolutely (from Lewis and Clark’s walk across America from Washington DC to the Oregon coast and back to Washignton DC that a group of people can cross the north American continent twice in less than 4 years. Now, these were not a tribe of “first-time-ever” stone age Indians/cavemen/Mongols (who conquered central Europe from China’s Mongonlian plains only a few centuries later in one generation), but the “it must have taken hundreds/thousands of years to populate North America/hunt North America/influence North America” is dead wrong.
Meat goes bad in 3-4 days. A tribe must continue to kill the easiest, largest, most productive, least dangerous target it can every day of the year. OR – and this is important – it’s “protectors” (the hunters) MUST deliberately seek out, target and then go out after and kill the most dangerous enemy in the nearby area to protect its own weak and susceptible targets (women and children) or there will be no second, third, or fourth generations. Thus, cave bears and saber tooth tigers disappeared soon after women and children came into the cave bear’s territory because they were a threat to the tribe. Large ground sloths and mammoths and the like disappeared because they were food.
Why did horses (a valuable asset) disappear? Don’t know.

Sturgis Hooper
Reply to  RACookPE1978
July 28, 2015 8:30 am

Horses were just another source of meat until domesticated.
Even during the advanced Solutrean culture, they were driven off the rock from which that distinctive phase of European development during the LGM takes its name.
North American Clovis culture is similar.

Reply to  RACookPE1978
July 28, 2015 8:56 am

Short-faced bears, sabertooth tigers, North American lions, North American cheetahs, and dire wolves were extirpated, while gray wolves, brown bears, cougars, and jaguars were not. Maybe the gone carnivores were vying with the humans for the gone herbivores.
DNA on stone butchering tools shows that Clovis people ate horses, camels, sheep, and bear.

Sturgis Hooper
Reply to  RACookPE1978
July 28, 2015 8:59 am

Finds of their blades show they killed mammoths.
Why did the megafauna of Caribbean islands survive while those on the mainland of North America died out?

Steve P
Reply to  RACookPE1978
July 28, 2015 9:00 am

“Meat goes bad in 3-4 days”
Not if it is smoked or otherwise processed. I recently posted about the Inoca and their buffalo hunts:

We remained a week in this place in order to dry all this meat. They make for this purpose a kind of cradle ten feet long, three feet wide, and four feet high, which they call gris, upon which they spread out their meat after preparing it. Under this they kindle a little fire. They are at it for a day, ordinarily, when they wish to dry a flat side. There are two of these in a buffalo. They take it from the shoulder clear to the thigh and from the hump to the middle of the belly, after which they spread it out as thin as they can, making it usually four feet square. They fold it up while still hot, like a portfolio, so as to make it easier to carry. The most robust men and women carry as many as eight, for a whole day. This is not possible in autumn nor in winter, however, as the cows are then very fat; they then can carry four at most.
According to most accounts, there were vast herds of Buffalo across N. America at the time of first contact. Any argument claiming that humans were the agent of the demise of the megafauna reaches an insurrmountable obstacle, in my view, at the presence of the huge buffalo herds in the historical record.
Although many native American tribes were at peace with each other via the ceremony of the calumet, others were keeping each other’s populations in check by constant warfare with their neighbors. These skirmishes were more on the order of blood feuds, but captives were taken, either to be slaves, or to be tortured, burned, and sometimes consumed.

Reply to  RACookPE1978
July 28, 2015 9:06 am

Sturgis Hooper: “…they were driven off the rock…”
Thanks for the link. What I found especially interesting is that the article refutes that claim:

More recent investigations showed, however, that the masses of horse bones were not under the cliff as could be expected but were in fact on the side and too far to fit the model. More convincing yet, the bones show little if any sign of the multiple fractures which would be there if horses had indeed jumped or fallen from the high cliff…
Currently accepted view proposes that hunters intercepted animal herds as they moved through the Solutré valley during their seasonal transhumance from the Alluvial Plain of the Saône to the Macônnais Uplands. They forced their prey into natural rock traps along the southern flank of the Roche just under the falt line where they could be slaughtered.

Sturgis Hooper
Reply to  RACookPE1978
July 28, 2015 9:15 am

True that the Solutreans used other techniques, too.
They employed similar strategies against reindeer and other game.
But some of the horses do show evidence of being driven off the cliff.

Reply to  RACookPE1978
July 28, 2015 9:27 am

“Why did the megafauna of Caribbean islands survive…”
Pygmy giant sloths on Cuba? Once humans arrived, they were goners.

Sturgis Hooper
Reply to  RACookPE1978
July 28, 2015 9:37 am

My point exactly.
The island megafauna were killed off by people much later, not by the YD, whatever its cause.
Here is a much better analysis of the effects of human hunting v. climate change in megafaunal extinctions than that committed by the Ship of Fools skipper.

Reply to  RACookPE1978
July 28, 2015 10:03 am

According to most accounts, there were vast herds of Buffalo across N. America at the time of first contact. Any argument claiming that humans were the agent of the demise of the megafauna reaches an insurrmountable obstacle, in my view, at the presence of the huge buffalo herds in the historical record.

But, until horses (Spanish invasion species, by the way) and the bridles and saddles and horse-training needed to use them were imported, the vast buffalo herds were simply too large – too many millions – to harvest successfully by people limited to walking speeds against a migrating herd. Killing one or two? certainly.
But it took technology and steel and gunpowder to remove them.

Reply to  RACookPE1978
July 28, 2015 10:26 am

Lewis and Clark’s journey took place 10,000 years after the large North American megafauna went extinct. The most accurate Pre-Columbian estimates are 2 million inhabitants for both Americas. ‘Pre-Columbian’ still implies 9,500 years after the extinction! So, it begs the question … how many humans existed on the North American continent, all 9.54 million square miles of it, 10,000 years ago, during the time of the extinction of the mammoths? Until you can answer that question, speculating about human hunting being the cause, with the air of certainty you give it, falls flat.

Steve Garcia
Reply to  RACookPE1978
July 28, 2015 12:22 pm

As to “from Washington DC” – sorry but no. Lewis and Clark left from the Mississippi River at St Louis and just south of the mouth of the Missouri River. Yes, they went to DC to talk to Jefferson, but they had all the time in the world to get from there to St Louis. THEN they stayed all winter.
As to them, remember that they had BIG rafts and stayed to the Missouri River, and that it took an entire winter to provision them. I KNOW: Over that winter, they provisioned themselves in my home town, across from St Louis. I seriously doubt that Clovis hunters took entire winters to provision themselves.
Recall, too, that they were specifically TASKED with discovering what was out there in the Louisiana Purchase that Jefferson had bought from France. Thus, they made a beeline to the coast. Nomads don’t do that.
And no, meat does not necessarily go bad in 3-4 days. Not even.
Just one hit on a Google search of “aged beef” – from and your point is shot down in the first sentence.

You know where you stand with steak, right? Twenty-eight-day aged beef is good. Get up to 35 or even 42 days of dry-ageing and, well, we’re talking ribeye royalty. All that steak needs is béarnaise sauce and a pile of hot, rustling frites, and there you have it: perfection.
Except that, for certain chefs, enough is never enough. What happens if you age beef for 60 or 90 days, they ask? How magical would that meat be? And then they do it. Which explains why we are now in the midst of an international steak-based arms race – one which the Dallas Chop House may have already won over in Texas, after it served a (and no, this is not a typo) 459-day aged steak last year. Eleven Madison Park in New York, meanwhile, has served a comparatively callow 140-day aged steak on its tasting menu (“stunt beef”, as one TripAdvisor wag had it)…

Aging meat was VERY common before refrigerators, and in all sorts of cultures.

Steve Garcia
Reply to  RACookPE1978
July 28, 2015 11:59 pm

verde – Yep. The meme that they ate only mammoth was one of the stupidest cases EVER of scientist’s jumping to conclusions.
There is plenty of literature out there describing that they also ate smaller game. SOME researchers actually questioned their orthodoxy and went out looking.
One telling piece of evidence is that the great majority of Clovis sites (1 or more Clovis tools) aren’t even out west. Most of them are in the US Southeast, where – interestingly – NO mammoth kill sites have been found. They had to eat SOMETHING, and it wasn’t mammoths. Not that shows up in the record in the sites in the SE.
It is amazing how much attention the put on the SW and W sites, for the public.

Steve Garcia
Reply to  RACookPE1978
July 29, 2015 1:46 am

verde – “Pygmy giant sloths on Cuba? Once humans arrived, they were goners.
— Read up on extinctions and the mechanisms behind them. Island fauna are the majority of victims of extinctions – specifically because they can’t get away. This has been know for many years.
And be aware that a major portion of the extinctions were not done by hunting the animals. It was the ignorant importing of alien fauna, which then in a new environment fund a niche which the indigenous fauna could not do anything about: The new ones ate up the old ones. Blame humans for ignorance, but then also admit that there was no intent.
YES, there were pests and predators, which WERE targeted – by farmers in times befoe the world realized the damage that was being done. When the world woke up to the extinctions, the world’s nations and groups of nations did a LOT to stop all of this. It isn’t QUITE fully stopped – rhinos killed for their honrs, etc. – and to HELL with the poachers who have done and are doing it. But don’t blame the entire human race cor soe criminals and their actions. WE – THE VAST MAJORITY OF HUMANKIND – have no part in those rinal acts, and aer doing all we can to stop it.
NOW, go to any list of extinct animals and COUNT them in that history, over time. You will find that extinctions are getting MUCH less common (in spite of the arm waving by greens).
So, what is real here is that animal lovers LONG AGO alerted the world to our responsibility to prevent extinctions. And LONG AGO all but a few of the billions of humans took it to heart and slowed the extinctions almost to a stop. No, the stop is not complete yet. Are we to be blamed FOREVER for things that happened around the world somewhere, in times before we were born, and suffer INDIVIDUAL guilt pangs forever because of what happened long ago or in some remote corner of the world? Someone made Julius Caesar extinct 2000 years ago. Should we cry about that, too?
The rending of cloth and the beating of our breasts has to stop somewhere. You and I aren’t to blame for any of it, and if you want to cry about what you aren’t doing anything to change, that ain’t my problem.

Steve Garcia
Reply to  RACookPE1978
July 29, 2015 2:19 am

Ockham – Quite true. Good and valid points.
It is a historical fact that animals on islands are MUCH MORE at risk of extinction than animals on continents, where they can just keep running away, to a large extent. Animals on islands simply run out of running away space.
Not true at all on N America. I’ve said since first hearing of the STUPID overkill theory of Paul Martin back in the 1970s or whenever, that it was an impossibility to prevent mammoths or dire wolves or any of the megafauna from escaping out into the vast expanses of the continent. 9.5 MILLION square miles and maybe 1.5 million humans in the northern part of the Americas, of whom 50% were women and perhaps 1/3 of the males were children. Leaving about half a million total humans.
Now, consider THIS – something most people don’t know anything about:
MOST Clovis sites are nowhere near the mammoth kill sites in the west and SW. Clovis primarily lived in the SE USA. Check with archaeologist Dennis Stanford about that one! And HOW MANY mammoth kills sites or mammoth bones have been found in the SE? Virtually NONE.
If you thought Clovis lived out west, think again.
And this “blitzkrieg” of Paul Martin’s?
If 3/4 of the Clovis men of hunting age lived in the SE, then you are down to about 125,000 Clovis hunters to cover all the western states and up into Michigan, where mammoths seemed to like living, and a bit beyond in the Midwest and NE. If one only talks about the USA, about 70% is in the regions where mammoths have been found. 3 million square miles, take 70%, and that makes about 2.1 million square miles. Round down to 2 million to be conservative. That is about 1 Clovis hunter per 16 square miles – a square 4 miles on a side or a circle about 5 miles in diameter. Standing on a flat plain, that is about as far as one can see, to the horizon in all directions. Hunting in packs of 4, let’s say, that is 64 square miles in which the animals have 360° of escape routes. Martin’s blitzkrieg is supposed to work with those numbers?
And WHY OR WHY if Clovis people lived in the SE, why would their hunters be 1,500 mile away, hunting elephant sized animals weighing 12,000 pounds? How much could 4 take back to Alabama or Tennessee from New Mexico? 100 pounds? In 4 travoises (sp?) maybe they could take 500 pounds each. Leaving 10,000 pounds lost t the vultures. No wonder that arkies think ancient men were stupid – the arkies project MONUMENTALLY stupid things on the ancient people and then sit back and feel superior.
At 30 miles a day, 1500 miles takes 50 days. With full a travois, cut that 30 down to 15. 100 days to get back. No one in their right minds would travel 1500 miles for 500 pounds of meat to feed their family – when they get back 150 days later. not when there is deer and boar and bear and rabbit and all sorts of other animals like half a mile away.
Paul Martin’s idea is DUMB.

Steve Garcia
Reply to  RACookPE1978
July 29, 2015 4:50 am

verde – I’d left this point behind and was on to other things when I ran across the following in a paper:

To establish that prehistoric humans not only could have caused extinction, but did so on multiple occasions, Martin [Paul S. Martin, the creator of the Overkill theory] turns to island settings. There is good reason for this, since it is extremely well documented that on island after island in nearly all parts of the world, prehistoric human colonization was quickly followed by vertebrate extinction…
…The magnitude of prehistoric human-caused vertebrate extinctions on islands came as a surprise when it first began to be described in detail by such scientists as Storrs Olson, Helen James, and David Steadman during the 1980s [73–75,81,84]. Nonetheless, it has long been known that island faunas are in general prone to extinction, and the reasons for this are well understood. Island vertebrates are vulnerable because their populations are small, because they are confined to well-delineated areas of land that may undergo rapid environmental change, because they may have lost (and in some cases have clearly lost) the behavioral mechanisms needed to cope with introduced predators, pathogens, and competitors, and because there is no ready source of conspecific individuals to replenish dwindling populations [11,50, 76,79,82]. Island faunas are, as Paulay has noted, “among the most vulnerable in the world”

That is from Grayson and Meltzer 2003 “A requiem for North American overkill“. (FULL TEXT)
Meltzer and Grayson are two biggies in this field, and seem to have probably been a thorn in the side of Martin, though Martin, I’ve heard, invited all side to the issue. So in that regard I respect him a lot.

Reply to  agfosterjr
July 28, 2015 10:42 am

@Sturgis Hooper: “Why did the megafauna of Caribbean islands survive while those on the mainland of North America died out?”
I suppose you ask rhetorically, but here are the obvious guesses:
1) Humans did not arrive till 5ky.
2) Cuban sloths were small for ‘megafauna’ (200kg).
3) First arrivals had no experience hunting them.
They lasted a thousand years after human arrival. The first arrivals were obviously boaters, and fishers. Sloths took a while to get on the menu. –AGF

Sturgis Hooper
Reply to  agfosterjr
July 28, 2015 11:00 am

It was rhetorical.
Caribbean ground sloths survived their kin on the mainland by 6000 years or more, and present a clear case of human predation to extinction.
IMO they qualify as megafauna, not just because they were large for their environment and related to species on the mainlands of the Americas, but since one threshold for mega status is 100 pounds and the other is 100 kg.

Steve Garcia
Reply to  agfosterjr
July 28, 2015 10:47 am

As to that “hunt big game” thing, there is a side to that that Clovis killed off the mammoths story that almost no one knows:
All the mammoth “kill sites” only number about 12 of them are unmistakably Clovis AND mammoth, and all of them are west of the Mississippi River, and north of the Ohio, in spite of the fact that the vast majority of Clovis “sites” are in the US Southeast. (A site is Clovis site if ONE Clovis artifact is found there.)
The same is true of mammoths in general – you can’t find mammoths in the Southeast, hardly at all. And if your brain suggests that the climate/environment decayed the mammoths fast in the SE, be aware that a good number of the mastodon finds are in Florida.
In other words, Clovis artifacts are found where the mammoth ain’t, and the mammoths are found where Clovis ain’t.
There are more than 12 sites claimed by someone to be a Clovis mammoth kill site, but one of the main experts on Clovis wrote a paper looking at them with a critical eye and had to toss most of those out, because of how the sites’ evidence was laid out.
With only 12 confirmed Clovis mammoth kill sites in a continent of 6 million square miles, the paper asked if 12 kill sites was enough for an overkill idea to be true.

Sturgis Hooper
Reply to  Steve Garcia
July 28, 2015 11:08 am

You could not possibly be more wrong.
What compels you to comment out of complete ignorance, when it takes just seconds to educate yourself?
Also, mammoths survived in North America long after the YD, indeed as recently as 7600 years ago in the then relatively human-free refuge of central Alaska.

Steve Garcia
Reply to  Steve Garcia
July 29, 2015 5:56 am

Sturgis Hooper – Yeah, you caught me. I said there were 12 confirmable Clovis-Mammoth kill sites. There are 14. I remembered the number wrong.
See Grayson and Meltzer 2003 “A requiem for North American overkill

How many of those genera can be shown to have been human prey during Clovis times? The answer is two – mammoth and mastodon—(Table 2) and there are only 14 sites that securely document this relationship [39]. As has long been known [42], this is not a sampling fluke (see Fig. 1). There are more late Pleistocene occurrences of horse than there are of mammoth or mastodon, and nearly as many for camel as for mastodon, yet there are no demonstrable kill sites for horse or camel or for any of the remaining genera [30,31,34,36,37,39]. This is not for want of looking. Given the high archaeological visibility of the remains of extinct Pleistocene mammals, and their great interest to archaeologists and Quaternary paleontologists alike, if such sites were out there, they would surely be found. Indeed, there is a strong bias in the Clovis archaeological record toward just such sites [33,67]. The rarity of megafaunal kill sites is such an evident feature of the late Pleistocene archaeological and paleontological records of North America that Martin has had to address it…
… Martin has attempted to account for the virtual absence of kill sites in an extraordinary way. He argues
that it all happened so fast that we should not expect to find empirical evidence of that process. That is, he has been forced to argue that “much evidence of killing or processing of the extinct fauna is not predicted” by his position [56, p. 397]. It is a rare hypothesis that predicts a lack of supporting evidence, but we have one here, and we have it only because evidence for it is, in fact, lacking.

“Martin” is none other than Paul S. Martin, the father of the Overkill theory. (FULL TEXT)
And I DO stand corrected in one respect. Thanks for that. Yes, there were some mammoths in Florida.
I can’t find the papers that discusses specifically why each excluded Clovis-mammoth kill site was excluded, but I cannot recall one of the 14 being in Florida.

Steve Garcia
Reply to  Steve Garcia
July 29, 2015 6:09 am

Sturgis Hooper –
You’ve gotta be kidding. Your “mammoths lasted until 7600 years ago” article is crap science. Utter crap.

Scientists have blamed the extinctions on everything from human overhunting to a comet impact to the introduction of novel infectious diseases.
The swiftness of the extinctions, however, is not suggested directly by the fossils themselves but is inferred from radiocarbon dating of bones and teeth discovered on the surface or buried in the ground, the researchers involved in the new study point out. Current “macrofossil” evidence places the last-known mammoths and wild horses between 15,000 and 13,000 years ago.
But hard remains of animals are rarely preserved, difficult to find, and laborious to accurately date because of physical degradation, the scientists said in a statement today.
So MacPhee and colleagues decided to tackle the problem by dating the creatures through dirt. Frozen sediments from the far north of Siberia and Canada can preserve small fragments of animal and plant DNA exceptionally well, even in the complete absence of any visible organic remains, such as bone or wood.
“In principle, you can take a pinch of dirt collected under favorable circumstances and uncover an amazing amount of forensic evidence regarding what species were on the landscape at the time,” said co-researcher Eske Willerslev, director of the Centre for GeoGenetics at the University of Copenhagen.

Hahahaha – SO what these guys are doing is scraping dirt samples ON THE SURFACE ABOVE THE PERMAFROST (which “can preserve small fragments of animal and plant DNA exceptionally well) that have had mammoth DNA on them FOR GOD KNOWS HOW LONG.
And THEN, do they date the DNA samples? NO! They date the dirt! THE DIRT! Those mammoth DNA samples might have been three for 7,000 years, with the permafrost “preserving” it “EXCEPTIONALLY WELL”.
Total crap science and assumptions about what it is their methodology is measuring.
And for DNA testing, why do they need to go to all that trouble to date the SOIL? WHY are they not just getting mammoth tusks from Alaska like everyone ELSE is doing? The things can be bought over the counter. And there is a good supply. My friend bought one up there a few years ago.
If they want good provenance, they can get one of the tusk finders and get him to take them to an in situ tusk. Not all tusks are “physically degraded”. That is total hogwash. They are mostly all intact, and MANY, MANY have been carbon dated. If they can’t do it on one tusk, go grab another one.
In fact, tusks are still used to make billiard balls and piano keys.

July 28, 2015 6:56 am

The lesson of Chelyabinsk is that meteors – even large ones – do not necessarily create craters. Cratering depends largely on the structural cohesiveness of the meteor. A loose aggregation of ice and/or stone and/or metal fragments could dump tremendous amounts of energy and debris into the atmosphere without cratering. OTOH, a *single* body large enough could create a crater without a noticeable wide-spread effect.

Steve Garcia
Reply to  tadchem
July 28, 2015 11:15 am

Basically, those are very solid observations. Yes, that was also to me the lesson of Chelyabinsk. With the loose aggregation ones, atmospheric entry and passage through the atmosphere will cause so much ablation that it never makes it to the ground, like Chelyabinsk failed to do. Ablation is the melting and vaporization that creates the fiery tail. Ablation happens on the front face of the meteor and doesn’t melt in very far at all – only a few millimeters at a time. The apparent size of the “fireball” is the expansion due to the vaporization. The thing that does it is, of course, the resistance of the air trapped in front, like a returning Space Shuttle. But the Space Shuttle is coming at much less speed (4 km/sec) than a meteor (usually about 15-30 km/sec).
Small, relatively solid ones – like Chelyabinsk – also can’t make it to the ground. By the time of the breakup – the big BOOM – over 90% of the Chelyabinsk meteor was already melted away. When it got smaller, it got more fragile, and the pressure on the front face eventually was too much for the amount of solid body that was left.
Your OTOH is correct, too. The Barringer Crater – “Meteor Crater” – hit only 50,000 years ago, in the very late Pleistocene, and made a a crater a mile across, meaning that the meteor was about 260 feet across – about 80 meters. And so far as we know, no wide-spread effect happened.
From both of these we can get an idea of how big a meteor has to be to cause wide-spread damage or have climatic effects. Tunguska was about 100 meters across, and it never made it to the ground. Possibly a steeper path allowed Meteor crater to make it all the way down. But none of these three was sufficient to be a Doomsday meteor.
All of that is good news. And it should, IMHO, suggest that if we ever DO find one with our name on it, that we DO have the option of nuking it and that breaking it up into a lot of smaller pieces doesn’t magnify the danger, but diminish it a LOT. We could take a few thousand Chelyabinsk meteors breaking up in the atmosphere and all we’d have is a lot of glass broken and a lot of people hurt. Even if all in one region (a possibility) that area would sustain a lot of damage, but still have a very good chance of making it through. But civilization would not be threatened with extinction. It’s the one BIG one that could really hurt.
And if Shoemaker-Levy 9 tells us anything, it is that if comet breaks up before arriving, it will string out so that the fragments arrive hours apart. So, even though the fragments are in basically a straight line, the time element means that they would hit different locations on a rotating planet. That is good, because it spreads out the risk.
How about ones that enter the atmosphere and THEN break up, so that they all arrive at the same time? An early breakup would first of all suggest a “friable” body – one that doesn’t have much “structuralk cohesiveness”. It would mean that we’d have a lot of Chelyabinsks (or less intact), and that there would likely be a lot of airbursts. But if less intact, they would break up even HIGHER in the atmosphere.
Chelyabinsk convinced me that airbursts are not serious risks to humankind. Big bangs, lots of noise. Big freaking deal? No. Something to tell the grandkids.

Matt G
July 28, 2015 7:17 am

Any comet or asteroid impact would not be able to keep dust in the atmosphere long enough for cooling to occur over thousands of years. It is extremely unlikely that they also would occur as often as number of events identified in the past. If the Platinum spike was from one then it was only coincidence not the cause.

Reply to  Matt G
July 28, 2015 9:14 am

One thing I found interesting was that it appears sea levels continued to rise rapidly through the Younger Dryas cooling period. Which is a bit counter intuitive for a major cooling event.

Matt G
Reply to  hell_is_like_newark
July 28, 2015 11:44 am

Sea levels were rising more rapidly prior to the YD event from the end of the last ice age and this cooling period slowed it down.

Steve Garcia
Reply to  hell_is_like_newark
July 29, 2015 12:43 am

hell –
Good observation But be aware that whether it was an impact or some other, as yet unknown, trigger, the YD DID begin VERY rapidly. Over a few years up to maybe 5-8 years ago, they kept finding that the suddenness was shorter and shorter, quicker and quicker – until they talked of it happening in like 20 years, and then perhaps even ONE year. Seriously, that was not what they expected nor what they could fit into their orthodoxy worth a damn. They admitted it was over their heads.
But just because the trigger was sudden does not mean that everywhere the ice masses could react/change as quickly. Even the whole length of the YD – 1300 or so years – is sudden in terms of ice ages coming and going. Ice neither advances suddenly over long distances nor retreats suddenly. The post-Wisconsinan period after 18,000 years ago was still warming up all the way up to the YD blipped and went cold 5,000 years later (with one short reversal in the middle – the FIRST Dryas, the OLDER Dryas).

Steve Garcia
Reply to  hell_is_like_newark
July 29, 2015 1:05 am

Matt G –
Yeah, that is a great graph of the sea level rise. Note the discrepancy between this and the same period on the Greenland ice core graph above.
On the ice core graph, there is a dive to almost as low as the YD, at about 16,000. That time on the sea level graph doesn’t show a flattening out.
This comment is not to disparage either graph, but to point out that the sea level graph has the line. If you look at the data points (the small black crosses) over various time intervals, you will see more variance in the data points than the line admits.
A better resolution graph is atcomment image
In particular, the straight line slope at the “Meltwater Pulse 1A”, there are LOT of data points around the lower end of the slope, and then a gap, and then only a couple of data points at about the upper end of it – and no data points in between. Al’s the pity there, because that gap allows ANY ONE of several lines in the Meltwater Pulse 1A time period. That approximately 70° slope could just as easily be near vertical, given how the large group of data points trend at the bottom (early part). Looked at blown up, that large lower group all seem to point damn near straight up. But the author of the graph chose to connect the slope almost directly to the first data point after the gap. The lower end of that slope aims almost directly at the data point BEFORE the large group. In effect, the large data group (about 13 points as I can count them) seems to be given no weight whatsoever; the line would be essentially the same without them even BEING there.
On THAT point I WILL disparage the sea level graph. A close examination of those 13 data points shows that their trend is very much nearly vertical. I’d guess an angle of about 85°. That SHORTENS the duration of the Meltwater Pulse 1A by about half. Even the BOTTOM end of that slope should be moved to LATER, IMHO. Those 13 data points should DOMINATE this period, and this graph shows no such dominance.
Can I accuse the authors of intruding gradualism onto an obviously sudden (catastrophic) meltwater pulse? LOL
Sometimes the devil IS in the details.